单项选择题
A.changed B.altered C.adjusted D.varied
I have spent a lot of time（）working on this problem.A.a...
单项选择题I have spent a lot of time（）working on this problem.
A.at B.–（不填） C.on D.with
She likes to spend time（）with her grandchildren.A.playB...
单项选择题She likes to spend time（）with her grandchildren.
A.play B.to play C.playing D.played
China is（）the east of Asia.A.inB.toC.onD.at
单项选择题China is（）the east of Asia.
A.in B.to C.on D.at
