The stair treads were covered with rubber to prevent slipping.楼梯踏板上覆盖着橡胶以防滑.He unwarily treads upon a viper asleep just before his feet.他不小心踩到正睡在他脚前的蛇上.So she treads lightly , trying to create a collegial atmosphere, una...
The older strata gradually disintegrate.较老的岩层渐渐风化.Contained within the rock strata is evidence that the region was intensely dry 15,000 years ago.岩层中有证据表明，该地区在15,000年前曾经非常干旱。We can follow the history of life through the ...