千斤顶的缺点是：（）
A.行程长
B.行程短
C.加工精度高
D.有冲击
参考答案：B, C
They were making a plan to help those students _____, which attracted me.
A．in brief
B．in public
C．in action
D．in need
脑膜炎球菌荚膜多糖疫苗
A．活疫苗B．死疫苗C．结合疫苗D．亚单位疫苗E．基因工程疫苗
