Question

这道题选哪个？

Answer 1

选D

追答

如果对这个回答满意，请点回答内容下面的“…”，再点击“采纳”，谢谢了！

题目已经说了：f(x)=sinx

Answer 2

∫f（x）dx=sinx
所以f(x)=(∫f（x）dx)`=cosx
f`(x)=-sinx,
f``(x)=-cosx
∫-xcosxdx=-∫xdsinx=-xsinx+∫sinxdx=-xsinx-cosx+C
选B

Answer 3

选A
1.当Not until位于句首时,句子要倒装.其结构为:Not until+从句/表时间的词+助动词+(主句)主语+谓语+.如:
①Not until the teacher came in did the students stop talking.直到老师进来学生们才停止讲话.
②Not until next week will the sports meet be held.直到下周才开运动会.
2. not until的强调结构为:It is / was not until+从句/表时间的词+that+.
上面两句改为强调句为:
③It was not until the teacher came in that the students stopped talking.
④It is not until next week that the sports meet will be held.