【正确答案】 B

【答案解析】at once：马上。immediately：马上。又如：It's getting late．We must go back home immediately.越来越晚了，我们得马上回家。 soon：很快。We' ll have lunch soon．我们很快就要吃中饭了。now：现在。If we leave now we'll be there before dark．如果我们现在就离开，我们在天黑前就到那里了。early：早。Mary gets up very early．玛丽起得很早。