黄铜管工作压力在()以下。
A、15MPa
B、20MPa
C、25MPa
D、30MPa
参考答案:C
.
---I did very well in the Maths exam yesterday.
---I did _____ . I got full marks.
A.no better
B.no worse
C.even worse
D.not better
水套加热炉是以天然气为传热介质。