Use the correct form of the word given in each sentence.
Câu 1: In 1978, a young pilot and his plane _____ after sighting a UFO, and they can never be found again. (APPEAR)
Câu 2: When coming to New Zealand, Albert was impressed by the beauty of the country and the _____ of its people. (FRIENDLY)
Câu 3: Although there are many _____ throughout the year, Tet is the most important festival for Vietnamese people. (CELEBRATE)
Câu 4: The advantage of living in the countryside is that the air is _____. (POLLUTE)
A.
B.
C.
D.