17. We'll have to finish the job.______.
A. long it takes however　　　　 B. it takes however long
C. long however it takes D. however long it takes
18. This restaurant wasn't_       that other restaurant we went to.  
A. half as good as     B. as half good as C. as good as half     D. good as half as
19. Lizzie was _____ to see her friend off at the airport.  
A. a little more than sad             B. more than a little sad  
C. sad more than a little             D. a little more sad than
17. D。however表示“无论如何也不；不管怎样”，引导让步状语从句，后面需要紧跟一个形容词或副词。however long it takes表示“无论花费多长时间”。
18. A。形容词倍数表达方法之一是“倍数词+as…as…”句型。
19. B。be sad to do sth.表示“做某事很难过”；more than表示强调，“非常”。