At times the balance in nature is ______, resulting in a number of possibly unforeseen effects.
A good teacher should encourage his students to ____ the knowledge by themselves instead of just copying and memorizing what the teacher said in class.
All of us are amazed at this______ temple, which has existed more than one thousand years.
John doesn’t work hard at his lesson and feels really nervous with the final exam _________.
Please excuse my _________ in without _________.
His ex-husband, whom she _________ last year, is now living in America.