can/could: 1. can 一般表示与生俱来的能力 或者一种客观可能性,还可以表 示请求和允许 。 Learning English _ be difficult. can Man can not live without air. _ I use your bike? Cancan/could: 2.在疑问句中，用could可表示请 求，语气较委婉。 _I have the television on? Yes, you _. / No, you _ Could He asks if he _ smoke here. could can/may cant/Im afraid notcan/could: 3.表示惊异、怀疑、不相信的态度。（ 主要用在否定句、疑问句或惊叹句中 ） Hes such a nice person that he _ commit the crime. cant 你怎么会如此地粗心！ How can you be so careless! Can this be true? can/could: 4. can never/canttoo表示“无 论怎样
