SGK Explore English - Trang 129
15 giờ trước (0:20)
Complete the sentences with the correct form of the verbs in parentheses.
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.
