单句语法填空
【小题1】(2019·全国Ⅰ)Modern methods __________ tracking polar bear populations have been employed only since the mid-1980s
【小题2】(2019·全国III)We were first greeted with the barking by a pack __________ dogs, seven to be exact.
【小题3】(2018·全国Ⅰ)The review says it is more effective at lengthening life __________ walking, cycling or swimming.
【小题4】(2018·全国Ⅲ)I was searching __________ these three western lowland gorillas I’d been observing.
【小题5】(2018·全国Ⅱ)Corn uses less water __________ rice and creates less fertilizer(化肥) runoff.
【小题6】(2017·全国Ⅰ)This trend, which was started by the medical community(医学界) __________ a method of fighting heart disease, has had some unintended side effects.
【小题7】(2017·全国Ⅱ)It ran for just under seven kilometers and allowed people to avoid terrible crowds on the roads above as they travelled to and __________ work.
【小题8】(2017·全国Ⅲ)After school she plans to take a year off to model full-time before going to university to get a degree __________ engineering or architecture.