The worsening of global warming, _____human activities are to blame, has led to frequently extreme weather.
| A．by which | B．for which | C．that | D．what |
About ___ of the teahers is our school ___ young people under thirty.
| A．two-five, are | B．second-fifth, is | C．two-fifths, are | D．two-fifths, is |
___Mr. Chen is waiting outside to speak to you. He appears to be quite ___ important person.
| A．/, an | B．A, an | C．The, the | D．The, / |
Suan! Where have you been? You have no idea ___ worried I was !
| A．how | B．what | C．that how | D．what |
___ my opinion, Americans eat too much meat.
| A．in | B．over | C．on | D．above |
Most Saturday evenings they cook meals ___ open fire outside.
| A．in | B．over | C．on | D．above |