--- Do you think people will have ________ work to do in the future?

--- I think so. And I think they will have _______ chances to travel.

A．fewer, more

B．little, many

C．more, less

D．less, more

在“探究杠杆的平衡条件”实验中，应先调节杠杆两端的平衡螺母，使杠杆在____________位置平衡，这样做是为了便于测量_______________。