He built a telescope ____ he could study the skies in his free time.
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It is imperative that you ____ here in time.
A. shall arive
B. must arrive
C. could arrive
D. arrive
There are two _____ in our school
A. library
B. libraries
C. librarys
Thank you for your help,_____ we could not have finished the work in time.
The landlady was very strict. She asked that we ____ television on week nights.
A. not watch
B. not be watching
C. must not watch
D. should not have watched
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