He wondered ________ his son was getting along with the experiment.
Good news-two of our classmates ______ into Tsinghua University in advance!
.Now natural disasters happen one after another, ______ warns man to treat nature kindly.
It is usually cool in April in Chongqing, but it sometimes ______ be rather hot for a few days.
Two decades ago this city was ______ but a small unknown town.
—Why didn’t you go to Shelly’s birthday party yesterday evening?—I ______ but I had an unexpected visitor.