It was his carelessness that ______ the accident. [ ]

ys many volunteers are working in areas ______ have dry climates, such as Kenya and Sudan.

― Why ______ you stay in the countryside, where it is not convenient to go shopping?―But I’ve found it rather valuable for my health.

Will your mother start to do the housework _______ she gets home

Some theories believe ____ quality input ensures quality output in English learning.