New Words：

sum [sʌm] n. 和，总和，总数；全部，一切
angle [ˈæŋɡl] n. 角；角度

Sample Sentences：

The sum of 7 and 12 is 19.
She paid the sum of $200 for dresses.

Please take pictures from a different angle.
An angle of 90 degrees is called a right angle.

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