—I have done well in the exam because of no careless mistakes.
—Congratulations! Students can never be _______ careful in exams.
| A．so | B．very | C．too | D．enough |
A person ________ email account is full won't be able to send or receive any emails.
| A．who | B．whom | C．whose | D．whoever |
She'll never forget her stay there ________ she found her son who had gone missing two years before.
| A．that | B．which | C．where | D．when |
Gun control is a subject ________ Americans have argued for a long time.
| A．of which | B．with which |
| C．about which | D．into which |
Whenever I met her，________ was fairly often，she greeted me with a sweet smile.
| A．who | B．which | C．when | D．that |
She brought with her three friends，none of ________ I had ever met before.
| A．them | B．who | C．whom | D．these |