Studies show that people are more_______to suffer from back problems if they always sit before computer screens for long hours.
| A．likely | B．possible | C．probable | D．sure |
After completing and signing it, please return the form to us in the envelope _______.
| A．provided | B．providing | C．having provided | D．provide |
The book was written in 1946, _______ the education system has witnessed great changes.
| A．since then | B．when | C．since when | D．during which |
He ______ be sitting at the gate, waiting for his lost son.
| A．used to | B．was used to | C．could | D．was accustomed |
It is often recommended that children _______ chances to get close to nature.
| A．must be offered | B．should offer | C．be offered | D．are offered |
If you _____ the bottle and cigarettes, you we’ll be much healthier.
| A．take off | B．keep off | C．get off | D．set off |