英语翻译1 in how many of integers between 1 and 100 does the digit 5 occur exactly once?A 10 B 18 C 19 D 20 E 21 为什么选B?2 What is the total number of different 5-digit numbers that contain all of the digis 2,3,4,7 and 9 and in which none of the odd digits occur next to each other?A 12 B 10 C 8 D 6 E 1 为什么选A?此题没读懂?3 the value of y will decrease as the value of x increases in which of the following equations?A y=x B y=x-2 C 2-y=3-x D 2x-y=4 E x+2y=1 为什么选E而不选

英语翻译
1 in how many of integers between 1 and 100 does the digit 5 occur exactly once?
A 10 B 18 C 19 D 20 E 21 为什么选B?
2 What is the total number of different 5-digit numbers that contain all of the digis 2,3,4,7 and 9 and in which none of the odd digits occur next to each other?
A 12 B 10 C 8 D 6 E 1 为什么选A?此题没读懂?
3 the value of y will decrease as the value of x increases in which of the following equations?
A y=x B y=x-2 C 2-y=3-x D 2x-y=4 E x+2y=1 为什么选E而不选A?
4 A rectangular playing field is 40 meters longer but 30 meters narrower than a nearby square playing field.How many more meters of fencing would be needed to enclose the rectangular field than to enclose the square field?
A 70 B 50 C 40 D 20 E 10 为什么选D?
5 A rectangular solid is twice as long as it is wide.The height of the solid is the average (arithmetic mean) of the length and the width,What is the ratio of the length to the height of the solid?
A 2 to 3 B 3 to 1 C 3 to 2 D 3 to 4 E 4 to 3 为什么选E?