29． When it thunders, we always see the light before we hear the sound．______ It’s because

It’s high time you had your hair cut ; it’s getting .

It’s also essential that we can not（）any marks mixed or damage to the cargo．

It"s getting rather late. It"s time we () home.

It’s time（）(采取措施) about the traffic problem downtown.

Practice 1　　No one knows what time itself is. We cannot see it. We cannot touch it. We cannot hear it. We know it only by the way we mark its passing. For all our success in measuring the tiniest parts of time, time remains one of the great mysteries of the universe.　　One way of thinking about time is to imagine a world without time. There could be no movement, because time and movement cannot be separated. A world without time could exist only as long as there were no changes. For time and change are linked. When something changes, you know time has passed.

—It’s said that Mo Yan’s speech was wonderful.—That’s true. We clapped our hands ______ many times during his speech yesterday.

I remembered the day when World War II finished I was eight or nine at the time , and we heard it ___ when we were at the table

I remembered the day when World War II finished I was eight or nine at the time , and we heard it ___ when we were at the table

It’s _______ that we will never forget.( )

—Hurry up, or we’ll be late.—Take your time. it’s just ______ short distance from here to ______ cinema.

It is high time we（）something to stop road accidents.