Not until he failed the exam _______he had left his books untouched .
| A．did he realize | B．had he realized | C．he realized | D．he had realized |
Brown said he was by no means annoyed;_____ he was glad to be able to make himself clearly understood.
| A．all in all | B．for one thing | C．on the contrary | D．by the way |
Peter had intended to take a job in business, butthat plan after the unpleasant experience in Canada in 2010.
| A． | had abandoned | B． | abandoned | C． | abandon | D． | will abandon |
According to scientists, our mental abilities begin to______from the age of 27 after reaching the highest level at 22.
| A．differ | B．shrink | C．fail | D．decline |
"It's a such nice place," Mother said as she sat at the table________ for customs.
| A．to be reserved | B．Living reserved | C．reserving | D．reserved |
The research lacks evidence, and therefore, its conclusions are doubtful.
| A．solid | B．fierce | C．severe | D．potential |