base

Exponentiation is a mathematical operation, written as bⁿ, involving two numbers, the base b and the exponent or power n, and pronounced as "b raised to the power of n". The logarithm is the inverse function to exponentiation. That means the logarithm of a given number x is the exponent to which another fixed number, the base b, must be raised, to produce that number x. The logarithm of x to base b is denoted as logb(x), or without parentheses, log_bx.

In chemistry, examples of bases are sodium hydroxide, calcium carbonate and potassium oxide. A base is a substance that can neutralize the acid by reacting with hydrogen ions. The soluble bases are called alkalis. Sodium hydroxide is an alkali. Copper (II) oxide is insoluble in water, so it is a base but not an alkali. Therefore, All alkalis are bases, but not all bases are alkalis. 在化学中，base的例子有氢氧化钠、碳酸钙和氧化钾。base是一种可以通过与氢离子反应中和酸的物质。可溶的base叫做alkali。氢氧化钠是一种碱。氧化铜不溶于水，所以它是base而不是alkali. Cupric oxide, or copper (II) oxide, is an inorganic compound with the chemical formula CuO. 铜的化合价有0、+1、+2、+3、+4，二价铜盐是最常见的铜化合物。价格、阶层。

Baseball is popular in North America and parts of Central and South America, the Caribbean, and East Asia, particularly in Japan, South Korea and Taiwan.

• not get to first base (with sth): not make a successful start (in a project); not even achieve the first step
• be off base: to be completely wrong
• touch base (with sb): to talk to sb to find out what is happening about sth
• cover (all) the bases: to make sure you can deal with any situation or problem so that nothing bad happens

Softball is a game similar to baseball played with a larger ball (11 to 16 in. circumference) on a field that has base lengths of 60 feet, a pitcher's mound that ranges from 35–43 feet away from home plate, and a home run fence that is 220–300 feet away from home plate, depending on the type of softball being played. It was invented in 1887 in Chicago, Illinois, United States as an indoor game. The game moves at a faster pace than traditional baseball due to the field being smaller and the bases and the fielders being closer to home plate. 垒球是一种类似于棒球的运动，在一个场地上使用一个更大的球（周长11到16英寸），该场地的垒长为60英尺，投手丘距离本垒板35到43英尺，本垒打围栏距离本垒板220到300英尺，这取决于所玩的垒球类型。它是1887年在美国伊利诺伊州芝加哥发明的一种室内游戏。这场比赛的节奏比传统棒球更快，因为场地更小，垒和外野手更接近本垒。