شرکت در آزمون آنلاین زبان انگلیسی 1 - زبان انگلیسی 1 | آزمون شماره 14030

Nobody knows exactly why the giant animals called dinosaurs died out. Most scientists think that its reason, most …, is the sharp decrease in the temperature of the earth.

By the time we finished working on the projects, it was dark and the first … of rain began to fall.

The underlined word “which” in the second paragraph refers to … .

Tom can’t go out with his friends tonight. He has to stay home and … care of his sick mother.