While he was ______ about in the street, Mary came up to him.
-What do you think of his opinion?-None has given me ________ piece of advice,so I will never take it.
If you keep on, you will succeed ________.
Everyone knows that________ is dangerous to play with fire, but________ is difficult is to prevent children from playing with fire.
—Thank you very much. —It’s a piece of cake compared to your saving my life: I am forever ______.
—Why are you so disappointed? —I went there hurriedly and waited there for 3 hours, ______ the tickets have been sold out.