6. Whoever invented______ wheel is believed to have made______ most useful invention in______ history.
A. a; the /; B. the; the; / C. the;. /; / D. a; a; the.
7. I spent the whole day repairing the motorbike. The work was _____easy.
A. nothing but B. something C. all except D. anything but
8. If you can make what the teachers teach ______, you will make rapid progress.
A. yours B. yourself C. you D. your
