若4x4yn+1与﹣5xmy2的和仍为单项式,则m+n=____
— Must I wash my skirt tonight?
— No, you . You can wash it tomorrow.
目前已知的动物大约有____ 种,这些动物按照身体内有无脊椎骨组成的脊柱可以分为____ 和____ 两大类。
How often ____you ____(go)shopping?