Jack can’tconcentrate on his lessons recently.— Yes, that might____why he did so badly in thelast test.[ ]

What are you reading, Jim? —I’m not really reading, just _____ the pages.

To keep fit, we should ______ a healthy eating habit.

下列语句中加点的字的解释，不正确的一项是（    ）

When facing a hard question, most people can’t give an answer ______.