此题要求改正所给短文中的错。对标有号的每一行作出判断；如无错误，在该行右边横线上面一个勾(√)；如有错误(每行最多只有一个错误)， 则按下列情况改正：
多一词：把多作的词用斜线(/)划掉，在该行右边横线上写出该词，并也用斜线划掉。
缺一词：在缺词处加一个字符号(∧)，在该行右边横线上写出该加的词。
错一词：在错的词下划一横线，在该行右边横线上写出改正后的词。
Early men did not have clocks. They were told time by the 76. ______
sun and shadows of trees. At first time, they used 77. ______
sticks placing in the ground instead of trees. They made 78. ______
marks in the ground, and the shadows from the sticks told 79. ______
the time of day. Later, men began to use sundials. Some of 80. ______
sundials were boxes with sticks cast a shadow. Men were 81. ______
able to take the sundial box with them. The mark for noon 82. ______
was very important. The sundials always have to face the same 83. ______
way or the time was wrong. Sundials were good only on sunny 84. ______
days, not on cloud days. They were the first kind of clock. 85. ______