1. I (learn) have been learning English for seven years now.

2. But l ast yea r I (not/ work) was not working hard enough for English, that's why my marks (not/be) were not really that good then.

3. As I (pass/ want) want to pass my English exam successfully next year, I (study) am going to study harder this term.

4. During my last summer holidays, my parents (send) sent me on a language course to London.

5. It (be) was great and I (think) think I (learn) have learned a lot.

1. Lan lives with her aunt.

=) Who does Lan live with?

2. I go to school by bike.

=) How do you go to school?

3. I am absent from class today because I am sick.

=) Why are you absent from class today?

4. Mai is talking to her new friend.

=) Who is Mai talking to?

Some students have portable CD players _______ small earphones

A. at B. with C. of D. of

\(99\frac{99}{100}\)

​Giải:

a)

- Công của lực kéo: A = F.S = 120.15 = 1800(J)

b)

- Công có ích để kéo vật: Ai = P.S = 100.15 =1500(J)

- Công hao phí: Ahp = A - Ai = 1800- 1500 = 300 (J)