1. Complete the sentences with the correct form of the verbs in parentheses.
(Hoàn thành các câu với dạng đúng của động từ trong ngoặc)
a. The United States (launch) __________ its first artificial satellite Explorer 1 in 1958.
b. NASA (prepare) __________ for another moon mission for many years.
c. He fell off the ladder while he (train) __________ for the program.
d. The plane (take off) __________ in 20 minutes.
e. I think soon we (know) __________ more about the origin of life on Earth.
Bài Làm:
a. The United States launched its first artificial satellite Explorer 1 in 1958.
b. NASA has been preparing for another moon mission for many years.
c. He fell off the ladder while he was training for the program.
d. The plane will take off in 20 minutes.
e. I think soon we will know more about the origin of life on Earth.