Robert is said ______ abroad ,but I don’t know what country he studying in .
题目
Robert is said ______ abroad ,but I don’t know what country he studying in .
A .to have studied B .to study C .to be studying D .to have been studying
选择哪个啊?
been 怎么使用?
答案
举一反三
已知函数f(x)=x,g(x)=alnx,a∈R.若曲线y=f(x)与曲线y=g(x)相交,且在交点处有相同的切线,求a的值和该切线方程.
我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
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