_____ to improving services, we will provide customers with all the information they need.
| A．Being committed | B．Having committed |
| C．Committed | D．Committing |
A booking-office is a place _______ tickets are sold.
| A．when | B．where | C．why | D．which |
This is the reason _______ he was absent.
| A．that | B．which | C．why | D．what |
Listening to loud music at rock concerts ____ caused hearing loss in some teenagers.
| A．is | B．are | C．has | D．have |
______ the task is difficult, they managed to complete it on time.
| A．Because | B．Therefore | C．As | D．Though |
That’s where I _______ live when I was a child.
| A．used to | B．was used to | C．was using to | D．am used to |