He could see the tall chimneys(烟囱) of the factory ______.
—What courses are you going to learn next term?—I don't know.But it's about time ________ on something.
The little child ________ go out alone at night, so he ________ walk in the dark that night.
—Did Ann fail in English?—She ________.Don't you notice that she looks depressed?
Look! There are so many mistakes in your composition. You ________ have fixed full attention on it.
Days later, I tried to get my sister to tell me what was going on, but she ________ say anything.