In the words unhappy and unusual，the "un" means _________．（ ）
A．veryB．mostC．notD．less
一 What were you doing at the time of the rainstorm yesterday？
一 I ________ at the library after school.
A．readB．was reading
C．am readingD．was read
一 I can't get on well with my family.
一 Why not talk with them？You should communicate ________ things become worse.
A．untilB．unlessC．afterD．before
一 I wonder if this glass is Tom's.
一 It ________ be his.His was broken just now.
A．mustn'tB．may notC．can'tD．shouldn't
Over the past few months，Chinese COVID vaccines （疫苗） ________ in many other countries.
A．have arrivedB．arrived
C．will arriveD．had arrived
一 Which dress do you prefer，the red one or the green one？
一 ________ .I like blue.
A．AnyB．EitherC．NeitherD．Both