1.A. knife              B. of                                  C. leaf                               D. life

2.A. although        B. enough                          C. paragraph                     D. cough

3.A. junk               B. sun                                C. put                                D. adult

4.A. headache       B. architect                        C.chemical                        D.children

5.A. aerobics         B.calories                          C.cycling                           D. doctor

Sai, phải là B

1. to have

2.leaving

3.seeing-cry

4.to have

5.talking-to finish

6.to disappoint

7.to try-to come

8.looking

9.to do

10.driving-riding

11.going

12.to write

13.firing

14.gambling

15.falling