Para.2 It is not very poisonous and it is present in the atmosphere in so small a quantity-only 0.034 percent-that it does us no harm. 它毒性不大，在大气层中的含量极小一只占0.034%一 一不会对我们造成任何伤害。 (1)poisonous:adj.containing or having the effect of poison有毒的 必 This medicine is poisonous if taken in large quantities. (2)do (sb.)harm/good;do harm good to sb./sth... 害有益 e.g.Smoking does harm to our health. (3)so+a.+a/an+n.+that如此.以至于 Para.2 ❖ It is not very poisonous and it is present in the atmosphere in so small a quantity — only 0.034 percent — that it does us no harm. ❖ 它毒性不大，在大气层中的含量极小——只占0.034％— —不会对我们造成任何伤害。 ❖ (1) poisonous: adj. containing or having the effect of poison 有毒的 ❖ This medicine is poisonous if taken in large quantities. ❖ (2) do (sb.) harm/good; do harm / good to sb./sth. 对…有 害/有益 ❖ e.g. Smoking does harm to our health. ❖ (3) so + a.+ a/an +n. + that 如此…以至于