孕妇缺钙可引起的是
A．腓肠肌痉挛
B．腰骶部疼痛
C．骨质疏松
D．骨骼疼痛
E．皮肤弹力纤维断裂
参考答案：A,C,D
使用与探伤面具有高对比度的颜色的（）。
He is clever and he can always _____ good ideas to solve problems.[ ]
A. think about
B. come up with
C. give out
D. think out
