4. It __________ to rain while we were studying at the library. A. was beginning B. began C. had begun D. begins
2 câu trả lời
4. It __________ to rain while we were studying at the library.
A. was beginning B. began C. had begun
D. begins
`⇒`Mệnh đề có chứa WHILE, chúng ta thường chia động từ ở dạng tiếp diễn.
4. It __________ to rain while we were studying at the library.
A. was beginning
B. began
C. had begun
D. begins
`->` while -> có 2 sự đang xảy ra.
-> tobe + V_ing
