Question 1: Jun _______ France for 4 monthѕ.

A. haᴠe learnt                B. learnt                         C. learnѕ                         D. haѕ learnt

Question 2: He had taught in this school before he _________ for London.

A. left                                                                   B. leave

C. leaving                                                             D. had left

Question 3: I _______ a flight to Korea for 5 ᴡeekѕ.

A. book                          B. haᴠe booked               C. haѕ booked                 D. bookѕ

Question 4: We _________ on the lake when it started to rain so we went home.

A. finished                                                            B. finishing

C. were finishing                                                  D. are finishing

Question 5: ____________ visited Toronto before your trip last summer ?

A. Have you ever                                                   B. You had

C. Had ever you                                                    D. Had you ever

Question 6: She__________ the gold medal in 1986.

A. win                            B. won                            C. to won                        D. B and C

Question 7: The man ___________ his letter in the post office at that time.

A. is sending                                                         B. was sending

C. sending                                                            D. was senting

Question 8: ________ you a teacher two years ago ? Yes, I _________

A. Is / isn’t                                                           B. Are / aren’t

C. Was / weren’t                                                   D. Were / wasn’t

Question 9: _________ they ________ the fish in the big bag last Sunday ?

A. Was / put                                                          B. Were / put

C. Did / put                                                           D. Do / put

Question 10: I ѕaᴡ mу beѕt friendѕ laѕt ᴡeek but I ________ them ѕo far thiѕ morning.

A. ѕaᴡ                            B. haѕn’t ѕeen                 C. didn’t ѕee                   D. haᴠen’t ѕeen

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A1 là hợp chất 2 nguyên tố của kim loại R; Trong hợp chất A1, R chiếm 71,43% về khối lượng. Tìm A1