请教托福语法

xueqiu (bmw)
1.Today's nuclear fission fuels are the remnants of (which) used to be a (much more) active mixture of radioactive and fissionable materials two billion (years ago) and (earlier).
2.Petrography (concerns) primarily with the detailed (description) and classification of rocks, (whereas) petrology deals primarily with rock (formation).
(#319988@0)
2002-1-1 -05:00

回到话题: 请教托福语法

回到论坛: HOME枫下论坛枫下论坛主坛工作学习求学深造

URL:   
http://www.rolia.net/zh/post.php?f=0&p=319988