题目

She hardly ever speaks French after class, for she is afraid ______ mistakes______ grammar. A  to make; of  B  of making; in  C  to make ;on  D  of making ;at 答案：B（2012•上海模拟）已知：⊙O1、⊙O2的半径分别是3和4，那么下列叙述中，一定正确的是（　　）A．当O1O2=3时，⊙O1与⊙O2相交B．当O1O2=1时，⊙O1与⊙O2内含C．当O1O2＜2时，⊙O1与⊙O2没有公共点D．当O1O2＞6时，⊙O1与⊙O2有两个公共点