Question

(1)单项选择

The research is so designed that once ________ nothing can be done to change it.

[　　]

A．begins

B．having begun

C．beginning

D．begun

(2)完成下面句子

过马路时一定要遵守交通规则。

________ the street, be sure to ________ the traffic rules.

Answer 1

答案：
解析：

解答：(1)D;(2)When crossing，follow

提示：

名师导引：题1中once begun等同于once the research is begun；题2中过马路用when +crossing作状语；follow表“遵守”。