20.“People who are sensitive can appreciate art better.” The relative clause in this sentence ( ).

20.Firms that use computers have found that the number of staff ( ) is needed for quality control can be substantially reduced.

19."If you frequently forget where you parked your car, there is an app that (could) be what you're looking for." The underlined word expresses ( ).

18."It (is taking) forever to upload an album." The underlined part expresses ( ).

17.One can never be happy if one is always envious ( ) others.

16.My mother (would have been) in Beijing by now if she had not missed the train. The underlined part in the sentence expresses a(n) ( ).

15.If you (would) kindly agree to the terms, we'll send you the samples right away. The underlined word indicates ( ).

14.A more flexible means of communication is always an advantage, ( ) being equal.

13. What leaves me with the deepest impression in the park is a(n)( ) trunk.

12. Lisa managed to save ( ) she could out of her low wages to help her sister.

11. She thought it advisable that a janitor ( ) against any possible intruder.