—Your English is very good.—
---What does “too young to do” mean?--- It means “_____ to do”.
--- Hello! Is that Tom over there? Long time no see. Let’s say hello to him.---Please _____ in the library.
---Mum, where did you put my sweater?---Is it _____ black one? I put it in _____orange box near your desk.
---Why didn’t you enjoy the talk?---It was __ _talk that I had ever listened to.
Frank often wears a mask _____ he can keep fit in the foggy and hazy (霾) weather.