It is possible to store solar energy ______ a number _____ days.

If we go on wasting water, there will be a shortage _____ fresh water _____ a few decades.

Unless we water these flowers, they'll die.

If _________________________________________________

Why don’t we collect empty bottles and cans?

I __________________________________

Thanks (1)_____ television, people can get the latest information and enjoy interesting programs (2)______ an inexpensive and convenient way. Nowadays, viewers can watch (3)_____ variety of local and international (4)____on different channels.