China’s population is expected to increase to about 1.5 billion in 2040, _____ it will start to decline slowly.
I wonder if he_____us, and I think if he_____us we’ll be able to complete the task ahead of time.
You won’t succeed_____harder.
_____ weather permits, we’ll have an outing.
_____ you go , you should bear the motherland in your mind.
I am going_____ you went last week.