40 According to this passage, why did the Vikings cover their sail in horse fat?
(A)To make it flexible.
(B)To make it light.
(C)To make it shallow.
(D)To make it stay dry.

A longship had a large, square, woolen sail, which the Vikings covered in horse fat to make it waterproof.

waterproof adj. 防水的； 耐水的

海盜將馬脂覆蓋在船身是為使船身防水。

The Viking北歐海盜，維金人 age lasted from AD 790 to 1100. The Vikings were mainly from Norway, Denmark, and Sweden, and were the best shipbuilders and seamen of their time.

They were able to travel long distances in their longships and attack towns on the coasts of Britain and Ireland. They reached Greenland, Iceland, and even America. The Vikings’ boats were long, narrow, light, and flexible.

They made them out of oak wood. The typical length距離, 長，長度 of a longship was about 20 meters. The hulls船體，船身 of the ships were shallow so that they could dock船用, 泊位；船塢 on beaches and sail in shallow water. A longship had a large, square, woolen羊毛製成 sail, which the Vikings covered in horse fat马脂to make it waterproof.

The main power for the longship was from the oars槳, which were all along the ship. There were usually a crew of about 60 men who rowed在水中移動, 劃（船） the boat.

The sailors水手，船員 usually placed their shields（舊時的）盾（牌） along the side of the boat for protection. They also carved the fronts of their ships into the shape of a dragon’s head in order to scare the enemies.