I saw him step forward momentarily but then hangback, nervously massaging his hands.
我看到他向前走了片刻,然后却退缩不前,忐忑不安地搓着手。
《柯林斯英汉双解大词典》
3
If you are making a long distance call on a public telephone and run out of money, give the number on your phone to the person you're talking to. Then hang up the receiver and he can call you back.