Bài tập thì quá khứ hoàn thành tiếp diễn Mai Duy Anh - August 11, 2022 0 1. I had … studying English for 5 years before I visited the USA. be been being None 2. He … the mountain when it started to rain. Had been climbing Had climbed Has been climbing None 3. … then, she had been working as a nurse at this hospital since 2019. Until From Since None 4. Had she … this survey for 2 days? Being researched Research Been researching None 5. Which project … you … following before moving to this project? Have - been Had - been Had - be None Please fill in the comment box below. Time's up