1．汤姆在学校表现不好。  
Tom                              at school.
2．他不介意在学校多待一小时。  
He                              at school for one more hour.
3．她经常帮我学习英语语法。  
She often                                                       .
4．如果你知道邮资，你就可以在任何窗口购买邮票。  
If you know about the postage you can                                                    .