I am happy with my old friends today.
| A．play | B．to play | C．playing | D．plays |
The policeman asked us _____him send the old man to the hospital.
| A．help | B．helps |
| C．helping | D．to help |
（）If there _____ no buying and selling of animals, there will be no killing in nature.
| A．is | B．will be |
| C．has | D．will have |
In summer milk will quickly go bad_____ it is put into a fridge.
| A．though | B．unless | C．because | D．once |
I still remember my first teacher we haven’t seen each other for many years
| A．for | B．because | C．since | D．though |