【推荐1】A recent film The Croods takes us back to a________(previous) undiscovered age known as the Croodaceous period,when Mother Nature was still experimenting. （所给词的适当形式填空）

【推荐2】________, I was caught in the heavy rain and got wet through from head to foot. (fortunate) (所给词的适当形式填空)

【推荐3】It has been proved that the training method can _____ (significant) improve the performance of professional athletes. (所给词的适当形式填空)