It is very difficult thelittle boy carry the big box.

You must cut up ______ onion and ____ tomato first.

You’d better try different ways you can think of maths problems. It’s good for you to learn maths well.

Rubbish in space has caused collisions, which would ______ produce more rubbish that threatens astronauts and satellites.

________its low cost, the appeal of iron as a building material lies in its strength, its resistance to fire, and its potential to span long distances