_________he is the son of the boss, he started from the lowest position as a common employee.
| A．Unless | B．Since | C．While | D．As |
Oct.1st, _________is our National Day, is always celebrated with singing and dancig.
| A．as | B．that | C．when | D．which |
Young people go to college with the expectation that_________educated people get a higher pay.
| A．good | B．better | C．best | D．the best |
Only when Tom fully recovered _________back to work.
| A．did he go | B．he went | C．had he gone | D．he had gone |
The couple finally bought the house they wanted, for they _______enough money.
| A．had saved | B．were saving | C．would save | D．were to save |
You look so tired. You________have stayed up late again.
| A．should | B．can | C．may | D．must |