2、根据所给汉语提示，完成下列句子。

1．His mother                              in the river．（禁止他游泳）

2．It                             he should apply for a patent for his invention．（这位发明家没有想到……）

3．Let’s discuss the problem this Friday afternoon                          ．（要是你方便的话）

4．Here was a chance for me                             that would catch snakes but not harm them．（通过发明某种仁慈的东西来表现一下自己）