Jack had to call a taxi because the box was _______ heavy to carry all the way home.

We often say that something is “as light as air”, but air is＿＿＿light. 

---- I was riding along the street and all of a sudden, a car cut in and knocked me down. ---- You can never be _______ careful in the street.

Trees are good for human being. We can’t plant them __________ many.

Hurry up, honey! We have to arrive at the airport by 11:00 o’clock, _____ we will miss the flight.