1. Dave / be / sad / because / he / not / pass history exam.

2. It / often / take / me / 15 minutes / get / school / foot.

3. My brother / can / play / chess / when / he / 6 years old.

4. The city/ suffer/ both/ air pollution/ water pollution.

5. My sister/ not only/ intelligent/ hardworking.

6. Friend/ advise/ me/ not/ go/ train/ next time.

7. I/ forget/ thank/ them/ help/ me.

8. Smoking/ not allow/ public places/ Australia