根据汉语提示完成句子

1. If you have any difficulty, please                        （让我知道）.

2. We always                                         （帮农民种树）when spring comes.

3. Lucy wants to                        （同……交朋友）more boys.

4. I passed the English exam                （由于）your help.

5. It                 （看来）the book is too difficult for us.

用工业酒精配置饮用酒可能会因含有那种物质而有毒（　　）

A．乙酸

B．乙酸乙酯

C．甲醇

D．甲醛