in your position,I would help him. [ ]
A. Was I
B. Were I
C. If I am
D. If I had been
B
发动机负荷较小时,发生爆燃的倾向几乎为()。
下列哪项是骨质疏松的典型症状()
A.疼痛
B.身长缩短
C.骨折
D.呼吸功能下降