________ unusual year 2020 is!
Yeah! The pandemic （大疫情） is a challenge not only to China but also to the world．（ ）
A．WhatB．What anC．What aD．How
Is that a new coat？
No，I_____it for a long time．（ ）
A．boughtB．have bought
C．have had
There aren't any libraries in our town，are there？
No，but it is said one_____next year．（ ）
A．will be builtB．is built
C．will build
I called you yesterday evening．But nobody answered．
Oh，sorry．Maybe I____in the bathroom at that time．（ ）
A．take a showerB．took a shower
C．was taking a shower
Miss Li，could you please help me____this math problem？
OK．Let me try．（ ）
A．look upB．work outC．set up
Must I wait here all morning？I have a lot of work to do．
No，you____．You may be back in the afternoon．（ ）
A．mustn'tB．can't
C．don't have to