The principle of the heating system in this building is that pipes ________ hot water from the boiler to every part of it.
23.I had reached a point in my career _____ I needed to decide which way to go.
22.Here are some new computer programs _____ for home buildings.
21._______ sweet and fresh, this kind of food is so popular with local people and the tourists.
20.Always read the label ______ you wash your clothes.
18.T appreciate that it's not easy for you, but you ______ try to get here on time.