If people _____ the importance of living a low-carbon life earlier, there _____ so many environmentalproblems now. [ ]

Perce Blackborow and his companions stayed on Elephant Island for six months before rescue came, so they ________ a lot of difficulties.

Usually children under six are not ______ to school except those of extraordinary intelligence.[ ]

sk given by the boss is ____ done, and we are to sum up our working experienceafter its accomplishment.

They had planted 10,000 trees of last month.