Scientists still wonder whether cloning will help or harm us and where it ____ us.

In the past few years, sea ice ____ in the Arctic as a result of global warming.

In the questionnaire, the subjects are questioned whether they____ no smoking in the public area.

They _______ on the program for almost one week before I joined them, and now we ________ it as no good results have come out so far.

--Why didn’t Tom have his lunch? It’s already one o’clock.---His pet bird ____this morning. He____still for quite a long time in his room crying.