6. Why don't we join a programme that helps the elderly?
 => Let's join a programme that helps the elderly 
7. The wall has too many advertisements and graffiti.
=> There are too many advertisements and graffiti on the wall
8. He has collected clothes for street kids for two years.
=> He started collecting clothes for street kids two years ago 

2. They began providing the elderly with cheap bus tickets some days ago.
=> They have provided the elderly with cheap bus tickets for some days
3. Although Jack is not rich, he gives the beggar some money.
=> Jack is not rich but he gives the beggar some money 
4. The students haven't participated in a clean-up programme since 2018.
=>The students last participated in a clean-up programme in 2018
6. Why don't we join a programme that helps the elderly?
 => Let's join a programme that helps the elderly 
7. The wall has too many advertisements and graffiti.
=> There are too many advertisements and graffiti on the wall
8. He has collected clothes for street kids for two years.
=> He started collecting clothes for street kids two years ago 

2. They began providing the elderly with cheap bus tickets some days ago.
=> They have provided the elderly with cheap bus tickets for some days
3. Although Jack is not rich, he gives the beggar some money.
=> Jack is not rich but he gives the beggar some money 
4. The students haven't participated in a clean-up programme since 2018.
=>The students last participated in a clean-up programme in 2018

6. Why don't we join a programme that helps the elderly?
 => Let's join a programme that helps the elderly 
7. The wall has too many advertisements and graffiti.
=> There are too many advertisements and graffiti on the wall
8. He has collected clothes for street kids for two years.
=> He started collecting clothes for street kids two years ago