题目

 --- Hello, is Mary in? --- I'm sorry she ____ come to the phone because she is having a bath. A. won't B. mustn't C. can't D. wouldn't 答案：. C。 解析: 查情态动词。答语意为“她正在洗澡，不能来接电话。”1．运用等式性质的变形，正确的是（　　）A．如果a=b，那么a+c=b-cB．如果$\frac{a}{c}=\frac{b}{c}$，那么a=bC．如果a=b，那么$\frac{a}{c}=\frac{b}{c}$D．如果a=3，那么a2=3a2