If children are asked to help with housework, they will feel needed. ______, they will learn to take care of themselves.
At minus 130℃, a living cell can be _________ for a thousand year.
Earth is believed ______ by an object the size of Mars at some point in the distant past before itssurface cooled.
our earth, or else it will be no longer fit for us to live on.
With temperature ______ so rapidly, we could not go with the experiment.
They've won their last three matches, I find a bit surprising.