The first man who cooked his food, instead

问题：

The first man who cooked his food, instead of eating it raw, lived so long ago that we have no idea who he was or where he lived. We do know, however, that (1) thousands of years food was always eaten cold and (2) . Perhaps the cooked food was heated accidentally by a (3) fire or by the melted lava from an erupting (4) . When people first tasted food that had been cooked, they found it tasted better. However, (5) after this discover, cooked food must have remained a rarity (6) man learned how to make and light (7) .

Primitive men who lived in hot regions could depend on the heat of the sun (8) their food. For example, in the desert (9) of the southwestern. United States, the Indians cooked their food by (10) it on a flat (11) in the hot sun. They cooked piece of meat and thin cakes of com meal in this (12) . We surmise that the earliest kitchen (13) was stick (14) which a piece of meat could be attached and held over a fire. Later this stick was (15) by an iron rod or spit which could be turned frequently to cook the meat (16) all sides.

Cooking food in water was (17) before man learned to make water containers that could not be (18) by fire. The (19) cooking pots were reed or grass baskets in which soups, and stews could be cooked. As early as 166 B. C, the Egyptians had learned to make (20) permanent cooking pots out of sand stone. Many years later, the Eskimos learned to make similar pans.

16（）

A.by

B.on

C.over

D.at