重点讲解：
1. focus on 集中(注意力)；关注；
The research effort has focused on tracing the effects of growing levels of five compounds.
研究重点追踪了5种化合物含量上升的影响tnOKVEHR#K^xg=Ia;。
2. along with 与…一起；
The baby's mother escaped from the fire along with two other children.
婴儿的母亲和另外两个孩子一起逃离了火海8_UM45T&*obC.p0~3!*。
3. at least （数量）至少，不少于；
He had been sitting on the document for at least two months.
他已经将这份文件压了至少两个月iWM9;7yR6s+DXs。
4. contend with 竞争；争夺；
It is time, once again, to contend with racism.
又一次到了与种族主义战斗的时刻了9G#xOb=k7aTEBHI。