Chọn đáp án đúng: Almost a hundred thousand people ... killed

Almost a hundred thousand people (1)________ killed and half a million homes were destroyed as a result of an earthquake in Tokyo in 1923. The earthquake began a minute before noon (2)______ people were cooking their midday meals. Thousands of stoves (3)______ overturned as soon as the earth began to shake. As a result, small fires broke out everywhere and quickly spread. It was impossible (4)______fire fighting equipment. Consequently, over ninety percent (5)______ the damage was caused by fire rather than by the collapse of buildings.
1. A. be B. was C. were D. have
2. A. what B. when C. where D. which
3. A. are B. were C. be D. was
4. A. using B. to use C. use D. used
5. A. of B. in C. with D. to
giải thk vs ạ