That could set off a “credit event,” ______ world financial markets into turmoil（混乱）, much as the collapse(倒闭) of Lehman Brothers ______ in the fall of 2008.
| A．threw；did | B．throwing；did | C．threw；had | D．throwing；had |
Not until she took off her glasses ______ she used to be my neighbor.
| A．I realized | B．I had realized |
| C．had I realized | D．did I realize |
The new teaching building ______ by the end of last month.
| A．has been designed | B．had been designed |
| C．was designed | D．would be designed |
Was it because Jack come late for school ______ Mr Smith got angry?
| A．why | B．who | C．where | D．that |
Most American children go to state schools, but the private schools ______ be very good.
| A．must | B．can | C．should | D．may |
Children should make ______ a rule to wash hands before meals.
| A．one | B．that | C．it | D．this |