1) It is a long time since we last met

A. We have already met after a long time

B. We have ever met for a long time

C. We have just met for a long time

D. We have not met for a long time

1) The last tim she sent me an email was 5 months ago

A. She has already sent me an email for 5 months

B. She has never sent me an email since 5 months

C. She has not sent me an email for 5 months

D. She didn't send me an email 5 months ago

1) She started using this washing machine last year

A. She has used this washing machine for a year

B. She has used this washing machine since a year

C. She used this washing machine for a year

D. She used this washing machine since a year

1) This is the first time Tom wnet abroad

A. Tom ever has gone abroad before

B. Tom has ever gone abroad before

C. Tom has never gone abroad before

D. Tom never has gone abroad before

1) Phuong phap dieu che SiO₂

1) Tai sao \(\dfrac{1}{2^{k+1}}=\dfrac{1}{2^k.2}\)

1) Viet chuong trinh nhap xau S1, tao xau S2 bao gom tat ca cac ki tu da xoa het chu so trong xau S1

1) Viet chuong trinh nhap xau S1, tao xau S2 gom tat ca cac chu so cua xau S1

1) So sanh nguyen nhan cua cach mang thang 10 Nga va cach mang thang 2

1) Lap bang so sanh cach mang thang 2 voi cach mang thang 10