This is my book. ________ that is your book.

We know _____better and _____ the unfinished workof perfecting the union falls to each of its citizens.

The fact has worried many scientists ______the Earth is becoming warmer and warmer these years.

What a thick fog! I went the wrong way at the corner and finally got lost.— It’s easy to make a wrong turn here even under an ideal weather________.

The post office is near here. You can go there _____ foot. You don’t need to go there _____ a car.