A propeller, in order to operate efficiently, must rotate at a relatively （） speed.

A、A.high

B、B.low

C、C.fast

D、D.lowly

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更多“A propeller, in order to operate efficiently, must rotate at a relatively （） speed.”相关的问题

第1题

[单选题] Click the Exhibit button and examine the data from the ORDERS and CUSTOMERS tables. Which SQL statement retrieves the order ID, customer ID, and order total for the orders that are placed on the same day that Martin placed his orders?（）

A、SELECT ord_id, cust_id, ord_total FROM orders, customers WHERE cust_name='Martin' AND ord_date IN ('18-JUL-2000','21-JUL-2000'); B、SELECT ord_id, cust_id, ord_total FROM orders WHERE ord_date IN (SELECT ord_date FROM orders WHERE cust_id = (SELECT cust_id FROM customers WHERE cust_name = 'Martin')); C、SELECT ord_id, cust_id, ord_total FROM orders WHERE ord_date IN (SELECT ord_date FROM orders, customers WHERE cust_name = 'Martin'); D、SELECT ord_id, cust_id, ord_total FROMorders WHERE cust_id IN (SELECT cust_id FROM customers WHERE cust_name = 'Martin');

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第2题

[单选题] Examine the data from the ORDERS and CUSTOMERS table. ORDERS ORD_ID ORD_DATE CUST_ID ORD_TOTAL 100 12-JAN-2000 15 10000 09-MAR- 101 40 8000 09-MAR- 102 35 12500 15-MAR- 103 15 12000 104 25-JUN-2000 15 6000 105 18-JUL-2000 20 5000 106 18-JUL-2000 35 7000 107 21-JUL-2000 20 6500 04-AUG- 108 10 8000 CUSTOMERS CUST_ID CUST_NAME CITY 10 Smith Los Angeles 15 Bob San Francisco 20 Martin Chicago 25 Mary New York 30 Rina Chicago 35 Smith New York 40 Linda New York Which SQL statement retrieves the order ID, customer ID, and order total for the orders that are placed on the same day that Martin places his orders?（）

A、SELECT ord_id, cust_id, ord_total FROM orders, customers WHERE cust_name='Mating' AND ord _ date IN ('18-JUL-2000','21-JUL-2000'); B、SELECT ord_id, cust_id, ord_total FROM orders Where ord_date IN (SELECT ord_date FROM orders WHERE cust_id = (SELECT cust_id FROM customers WHERE cust_name = 'MARTIN')); C、SELECT ord_id, cust_id, ord_total FROM orders Where ord_date IN (SELECT ord_date FROM orders, customers Where cust _ name = 'Martin'); D、SELECT ord_id, cust_id, ord_total FROM orders WHERE cust_id IN (SELECT cust_id FROM customers WHERE cust name = 'Martin');

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第3题

[单选题] The term power-driven vessel means（）in these Rules.

A、any sailing vessel with propelling machinery B、any vessel propelled by machinery C、any sailing vessel with or without machinery for propelling D、any sailing vessel with propelling machinery not in use

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第4题

[单选题] “Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired, or at least patched up temporarily until the next stop” This sentence means that （）.

A、Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired on the spot B、Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired on the next port of call C、Any leaks in piping, propeller shaft, machinery, tanks, will have to be repaired until the next stop D、Any leaks in piping, propeller shaft, machinery, tanks, will have to be at least patched up

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第5题

[单选题] Kort nozzles are installed around the propellers of some vessels to（）.

A、Increase the thrust of the propeller B、Protect the propeller from striking sawyers C、Prevent the propeller from striking barges towed on the ship D、Prevent the propeller from touching bottom in low water

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第6题

[单选题] The pitch of a propeller is a measure of the（）.

A、angle that the propeller makes with a free stream of water B、angle that the propeller makes with the surface of the water C、number of feet per revolution the propeller is designed to advance in still water without slip D、positive pressure resulting from the difference of the forces on both sides of the moving propeller in still water without slip

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第7题

[单选题] For vessels with （）, the meaning of the order would include the combination of pitch and revolutions as indicated in ships orders.

A、fixed pitch propellers B、uncontrollable pitch propeller C、constant pitch propellers D、variable pitch propellers

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第8题

[单选题] The difference between Fixed pitch propeller (FPP) and Controllable pitch propeller (CPP) is in that（）

A、for FP, once fitted, the position of the blades can also be changed in operation B、for CP, once fitted, the position of the blades can also be changed in operation C、the CP type has a relatively smaller hub compared with the FP propellers D、the FP type has a relatively larger hub compared with the CP propellers