The out﹣of﹣door world is （31） 　　of secrets．There are so many secrets，and they are so interesting that （32） 　　men and women，boys and girls are busy （33） 　　them．There are all kinds of animals and plants around us．The facts about how they live and grow （34） 　　interesting．

Do you know that one of the （35） 　　presidents of the US spent hours and hours studying birds？A businessman lives near New York City．He became so interested in insects that he began to （36） 　　them．He now has over one hundred different kinds of insects．He keeps them carefully in glass boxes．

Now come with me，and I will help you find some of （37） 　　secrets．Let us go quietly （38） 　　the forests．Here we shall find how a hare （39） 　　other hares where there is （40） 　　．We shall follow a mother bear and her young ones when they try to （41） 　　food and （42） 　　for their long winter sleep．We shall watch bees dancing in the air to tell other bees （43） 　　they can find food．I will show you （44） 　　other interesting things，but the best thing I can teach you is to keep your eyes and ears （45） 　　when you go outdoors．

31．A．fill	B．filled	C．full
32．A．thousands of	B．thousand	C．thousand of
33．A．to study	B．studying	C．study
34．A．are	B．is	C．have
35．A．more famous	B．famousest	C．most famous
36．A．find	B．take	C．collect
37．A．nature's	B．nature	C．natures'
38．A．across	B．through	C．cross
39．A．says	B．tells	C．talks
40．A．dangerous	B．safe	C．danger
41．A．lookup	B．look after	C．look for
42．A．prepare	B．ready	C．provide
43．A．when	B．where	C．that
44．A．many	B．much	C．a lot
45．A．open	B．opening	C．opened