— My leg hurts a lot.— You’d better go to the doctor and have it _____.
These viruses, if ________ in, can result in illness or even death.
Please take down my telephone number ________ something important happens.
Mountain climbing ________ be very tiring, and many people feel sick ________ the atmosphere gets thinner.
It is generally considered unwise to give children ________ they wants.
Without facts, we cannot form a worthwhile opinion for we need to have a factual knowledge ________ our thinking.