While every possible means __________ to prevent the river pollution, the river in my hometown has still not been restored to its past beauty

―Does the rule work―Yes, students are absent.

My grandma ______ to see me .Please help me to buy some food.

tural disasters happen one after another, ______ warns man to treat naturekindly.

There is no doubt，in my opinion， ________matters is not the speed，but the quality of the product.