根据短文内容，选择正确答案。

    There were many famous explorers during 1400--1600. What were the names of the most famous explorers? What were the major achievements of the famous explorers? This website provides what you want to know.

    Famous Canadian Explorers   The discovery of the New World opened up new colonies(殖民地) in Canada. One of the most famous Canadian explorers was Louis Joliet who explored the Great Lakes area and discovered the Mississippi River.

Famous Spanish Explorers Famous Spanish explorers explored the Caribbean and South America. Just a few famous Spanish explorers conquered (征服) millions of local people who made up the nations of the Incas and the Aztecs. Famous Spanish explorers included Hernando Cortes, Francisco Pizarro, Hernando De Soto, Vasco Nunez de Balboa and Juan Ponce de Leon.

Famous English Explorers The most famous English explorers started their voyages of discoveries during the Elizabethan reign of Queen Elizabeth I. The most famous English explorers included Sir Walter Raleigh, Sir Francis Drake, Sir Martin Frobisher and Sir John Hawkins.

    Famous Portuguese (葡萄牙的) Explorers   The famous Portuguese explorers led the way when it came to exploration. The most famous Portuguese explorers included Ferdinand Magellan, Vasco da Gama, Bartholomeu Dias and Miguel Corte-Real.

1.2除4与 $2\frac{2}{5}$ 的差，商是多少？

棱长为1的正方体ABCD A₁B₁C₁D₁中，点M、N分别在线段AB₁，BC₁上，且AM=BN，给出以下结论:
①AA₁⊥MN
②异面直线AB₁，BC₁所成的角为60°
③四面体B₁ D₁CA的体积为$\frac{1}{3}$
④A₁C⊥AB₁，A₁C⊥BC₁,，其中正确的结论的个数为(　　)

霉喜欢在____的环境中生长。