有一串单项式：x，-2x²，3x³，-4x⁴，5x⁵，…，19x¹⁹，-20x²⁰，…，则第100项是______，第n项是______．

It was a very hot day in the middle of summer, and there were no trees along the street. Mr. Read (41) his shop at half past five, and went out into the street and began walking to the bus. He was a very (42) man. The sun shone straight down the street, and in a few minutes Mr. Read (43) very hot.

A. shoesB. arms C. car

A small boy came out of another (44) in the street and followed Mr. Read. He stayed very (45) him all the time, and he kicked Mr. Read’s (46) several times. Mr. Read looked at him angrily each time.After the fourth time, Mr. Read stopped, turned (47) and said to the small boy, "What are you doing (48) following me like that! You’re going to hurt my feet."
"I’m (49) , but don’t stop me, please!" the small boy said. "It’s very hot today, and there isn’t (50) shade anywhere else in the street!\