John said he'd been working in the office for an hour,_______was true.
| A．he |
| B．this |
| C．which |
| D．who |
－Jeffery seems to go without proper food and sleep for days.
－Leave him alone.That's________he reacts to a lost love.
| A．what | B．how |
| C．why | D．when |
She________the opportunity，but unfortunately she just let it go.
| A．should have taken | B．must have taken |
| C．needn't have taken | D．can't have taken |
I don't remember who came first，but we all________the lecture.
| A．attend | B．attended |
| C．have attended | D．are attending |
We can't avoid negative thoughts，but we should make it a habit to replace each negative thought with a positive________．
| A．one | B．ones |
| C．the one | D．that |
Clive Palmer，the designer of Titanic II，________to answer questions about the project's cost.
| A．abandoned | B．declined |
| C．decreased | D．regretted |