导致结构产生变形的外力，包括弯曲力、扭力、冲击力、（）、压力等多种。
参考答案：拉力
The fans never expected their favourite team, which owns so many excellent players, ________have been defeated in the first round!
A．must
B．should
C．might
D．could
以N2为载气，使用TCD检测器无法检测到的组份是（）。
A.甲烷
B.氮气
C.二氧化碳
D.氢气
