题目

In my opinion, all Mr Tom ______ good to his students in his class at present. He is very strict in their study.  A. does does does    B. does do do   C. does does do      D. did do does 答案：C 解析: Mr Tom does为定语从句修饰all,后面的does do是谓语动词的强调形式。Do good to是“对…….有好处”的意思。14．$\sqrt{（x+\frac{2}{3}）^{2}}=x+\frac{2}{3}$成立的条件是x$≥-\frac{2}{3}$．