【单选题】
The（）is fitted in the main steam supply line and is usually of the non-return type.
A、main steam stop valve
B、auxiliary steam stop valve
C、feed check or control valve
D、blow down valve
查看正确答案
A、In the 13th century a Black Rod went between the two Houses of Parliament for liaison and to discipline the members. B、In the 13th century Parliament only met by royal invitation. C、In the 13th century Parliament's role was to offer advice,not to make decisions. D、In the 13th century the most important part of Parliament was the House of Lords.
