The development of industry has been ________ gradual process throughout ________human existence，from stone tools to modern technology.
| A．不填；the | B．the；a |
| C．a；不填 | D．a；a |
Listening to peaceful music. as well as taking exercise,___________ a lot in relieving people 's sad emotions.
| A．help | B．helped | C．helps | D．are helping |
The man__________has made up his mind to win will never say "impossible".
| A．whom | B．when | C．which | D．who |
Only when___________ according to the directions can the medicine be quite effective.
| A．taking | B．taken | C．being taken | D．having been taken |
To be successful, you need to remember that ___________you might be very busy, you need to be energetic and enthusiastic.
| A．as though | B．in case | C．even if | D．now that |
Not until all the fish died in the lake __________ how serious the pollution was.
| A．did the villagers realize | B．the villagers realized |
| C．realized the villagers | D．do the villagers realize |