Our children are interested in giving away their old books to needy people.

A. Our children find it interesting to give away their old books to needy people

B. For our children, it is interesting for needy people to give away their old books.

C. One of the most interesting things that our children do is to give away old books to needy people.

D. Giving away old books to needy people is one of our children’s hobbies.

Mark the letter A, B, C or D to indicate the underlined part that needs correction in each of the following questions.

Don't forget calling me as soon as you arrive here.

A. Don't

B. forget

C. calling

D. arrive

Cho ∫ 2 9 f ( x ) d x = 6 . Tính ∫ 0 a x 2 − 1 x + 1 d x = 3 2 .

A. a = 3

B. a = 4

C. a = 5

D. a = 2