1949年中華人民共和國的建立，標志著中國從半殖民地半封建社會進入_________。
________(fail)severaltimes,theyneedsomeencouragement.
求曲線y=x^2與直線y=0，x=1所圍成的平面圖形繞x軸旋轉一周所得旋轉體的體積V.
Othersarguethatsincetheearthhasenduredalongstringoficeagesinthelasttwomilliontothreemillionyears,anywarmingis________tobetemporary.
Insomeschoolschildrenwhoprefertoreadbooksratherthan________footballbecomesocialoutcasts(被拋棄者).
