16. The board of the company has decided to ________ its operations to include all aspects of the clothing business.

A) multiply B) lengthen C) expand D) stretch

17. His business was very successful， but it was at the ________ of his family life.

A) consumption B) credit C) exhaustion D) expense

18. First published in 1927， the charts remain an ________ source for researchers.

A) identical B) indispensable C) intelligent D) inevitable

19. Joe is not good at sports， but when it ________ mathematics， he is the ‘best in the class.

A) comes to B) comes up to C) comes on to D) comes around to

20. Doctors warned against chewing tobacco as a ________ for smoking.

A) relief B) revival C) substitute D) succession

16-20 CDBAC