求解释下这几道新GRE题

1. Gluten---a protein found in wheat, barley, and rye--- was formerly avoided only by those suffering from celiac disease but has recently become a popular dietary ______, with gluten-free food popping up everywhere.

A. fad B. substitute C. panacea D. scam E. villain

2. The flood of new candidates, including newcomers, party veterans, and the first female candidate, is a startling (i)_____ Japan's (ii)_____ political succession. The crowded field means that the selection of the new prime minister, instead of being customary(iii)_____, backroom affair, has become a source of intense public excitement.

A. abbreviation of D. scripted G. conspicuous
B. illustration of E. chaotic H. celebrated
C. departure from F. prolonged I. dry

3. Arguments based on mere possibilities (i)______ the difficulty of discussing future technology, not least since they (ii)______ public debates on technological options. A mere possibility argument such as "Agricultural biotechnology can have serious effects on ecosystems that we still know nothing about" can be taken by opponents of the technology to be (iii)_____, whereas proponents tend to dismiss it completely.

A. epitomize D. polarize G. decisive
B. mitigate E. forestall H. empirical
C. outweigh F. undergird I. dogmatic

单空题看了答案才知道错哪了，三空题还是不会，会做的麻烦解析一下思路。