______ is known to us is that tobacco contains nicotine and other harmful products, so you should give up smoking.

Sorry, we are late. We _______ to be here at six o’clock.

Such a problem is＿＿＿＿difficult for a primary school student ＿＿＿.

_______ healthy, my brother goes hiking on weekends.

I haven’t seen film star Sally for a long time.—She ________ the stage because she gave birth to a baby last year.[ ]