The twins usually come to school ______their father’s car.[ ]

Is this the reason ______ at the meeting for his carelessness in his work?

Timmy goes to school __________ every day. It’s 5 minutes’ walk from his home to school.[ ]

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.

My headache _________ me. I thought it was going away, but now it’s getting worse.