I'm havingtroublepayingattention- I have a thing or two on mymind.我现在很难集中注意力——我心里有事。
Why don't youaskAndrew about it? Heknowsa thing or twoabout(= has someknowledgeof)computers.这个问题为什么不问问安德鲁？他懂点计算机。
Shethinkssheknowseverything aboutraisingchildren, but Icouldtellher a thing or two(= someinformationshe does notknow).她觉得自己对于养育孩子样样精通，不过我倒可以让她见识一二。