The manager said to the employees at the meeting that everyone must___their attention to efficiency
| A．concertrate |
| B．focus |
| C．pay |
| D．fix |
______ yourself, you should never put convenience before safety.
| A．Protecting | B．Having protected | C．Protect | D．To protect |
The past year has seen people around the world honoring Nelson Mandela, _____ passed away on Dec 5 at the age of 95.
| A．who | B．which | C．that | D．when |
The aging population _____ each day .There must be some kind of interesting activity for the old.
| A．has grown | B．grew | C．will grow | D．is growing |
When I ______to take part in the sport, I felt very surprised because I had never done this before.
| A．was chosen | B．chose | C．has been chosen | D．had chosen |
I asked her ______ I should do to lose weight, and she told me to balance my diet.
| A．why | B．that | C．what | D．how |