3. The train ______ half an hour ago.
A. has been leaving
B. left
C. has left
D. had left
4. Jack ______ the door.
A. has just painted
B. paint
C. will have painted
D. painting
7. He has been selling motorbikes ________.
A. ten years ago
B. since ten years
C. for ten years ago
D. for ten years
8. Christopher Columbus _______ American more than 500 years ago.
A. discovered
B. has discovered
C. had discovered
D. had been discovering
Làm và giải thích ạaaa <3333
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