Lesson 4 An exciting trip

1.       receive a letter from / hear from

2.       a great number of / a great amount of / a large sum of

3.       in the center of / in the middle of

4.       fly to Perth/ fly a plane to Paris / fly them to Wuhan

5.       find his trip exiting / find sb. doing sth/ find the shop closed

6.       He is working for a big firm. 现在进行时表示说话期间持续发生之动作，试比较其于完成进行时态之区别

7.       a big firm / a small company/ a Limited Corporation