In our school, students are            according to how much they know and how old they are.

When we visited Hainan again ten years later, we found it changed so much that we     could hardly _______ it.

As is widely acknowledged, a great number of traffic accidents ____ numerous deaths and countless property loss all over the world every year.   

However, at times this balance in nature is disturbed, _______ a number of possibly unforeseen effects.

—Do you know if Mary has got married   John?—Yes, They have  for nearly a year.