．The theory is true _______ the hotter a body is, the more energy it gives off

Listen ! Helen is singing in the next room.—It __________ be Helen. She is in Tianjinnow.

Making a proper choice ______ the future will probably make much difference in our life

“ Double 11” somewhat overlaps with Valentine’ s Day and provides another occasion for lovers to buy each other gifts, most spending on that day doesn’t involve a change of single status.

下列各句中，加点字解释正确的一项是