_____________ hard you try，it is difficult to lose weight without cutting down the amount you eat.
| A．Whichever | B．Whatever | C．However | D．Whoever |
Experiments of this kind _______in both the U.S. and Europe well before the Second World War started.
| A．have conducted | B．have been conducted |
| C．had conducted | D．had been conducted |
Robert is said________ abroad, but I don’t know what country he studied in.
| A．to have studied | B．to study |
| C．to be studying | D．to be studied |
We live in an age ________ more information is available with greater ease than ever before.
| A．why | B．when | C．to whom | D．on which |
Tom took a taxi to the airport, only _____ his plane high up in the sky.
| A．finding | B．to find | C．being found | D．to have found |
The market competition is fierce, but our products have great advantage ______ quality and price.
| A．in place of | B．in view of | C．in case of | D．in terms of |