．—Alice, you look puzzled．Haven’t you understood it?
—Yes．I _of another problem just now．
| A．had thought | B．have thought | C．thought | D．was thinking |
A good advertisement should ____ the consumers and direct their attention to the product.
| A．absorb | B．attach | C．call | D．attract |
I don’t think the experiment is ______ failure, because it has provided us with _____ valuable experience for our future tests.
| A．不填; 不填 | B．a; 不填 | C．a ; a | D．不填; a |
____ you know your potential（潜力）, you have to rely on many other people to get to where you are.
| A．While | B．Since | C．If | D．Where |
. It was not until Maggie had arrived at her office _____ her appointment with the doctor.
| A．did she remember | B．had she remembered |
| C．when she remembered | D．that she remembered |
.When _____ my childhood, I get lost in happy memories of times now gone forever.
| A．looking out for | B．looking forward to |
| C．looking back on | D．looking down on |