No one knows ______ the task will last. What a pity!A．how long

_______ I finish the work today—No, you needn’t.

It is human activities on the earth that are to _______ global warming.

ink everyone has a role to play inmaking the planet a better place.—Yes, indeed. ______.

(2013·天津，11)It was not until near the end of the letter________she mentioned her own plan.