The two girls are so alike that strangers find ____ difficult to tell one from the other.
—I sent him a most interesting storybook by mail this morning. —You __________ so; he's coming tomorrow morning.
I was not __________ her presence till she spoke to me.
People all over the country felt shocked __________ they heard of the news __________ eight children were killed at the school gate.
I must apologize for __________ ahead of time.
You must __________ the key information in the text if you want to choose the correct answer.