下列各组大写字母中，他们的小写字母只占中格的是________ .

We’re looking forward to _____a chance to watch the opening ceremony of the London 2012 Olympic Games. [ ]

It’s going to rain. ________a raincoat with you.—OK, Mum.

________ really enjoyable, ____________ us a valuable lesson.

With your brother’s help, I’ve made great progress in English and I really want to do something for him ____