There were 12 frogs sitting on a log by a pond, but 3 frogs hopped away. How many frogs are left?
译句：池塘旁的园木上坐着12只青蛙，但是现在3只青蛙跳走了，还剩下多少只青蛙？
答案：9
词汇：
log /lɔɡ/
n. 航行日志；园木；记录
vi. 伐木
vt. 伐木；航行
[近义词]：
n. wood, firewood, written record
v. record, cut down
[惯用语]：
log on 注册
log file 日志文件
like a log 象木头一样不动；无知觉的
log cabin n. 小木屋
log off 注销，退出系统
log out 注销；退出系统
ship's log 航海日志
[例句]：
• Lincoln was born in a humble log cabin.
林肯在一个简陋的小木屋里出生。
• He logged the ship's speed at 10 knots.
他在航海日志之中记下船速每小时十海里。
• They logged the timber into 7-foot length.
他们把那根木材锯成七英尺长。
pond /pnd/ n. 池塘
[惯用语]：
lotus pond 荷花池，荷塘
fish pond 鱼塘，鱼池
[例句]：
• The pond iced over during the night.
水池在夜间结冰了。
• These are many beautiful buildings, bridges and ponds.
这里有许多美丽的建筑、桥梁和池塘。
hop /hɑp/
vi. 单足蹦跳, 跳上跳下
vt. 跃过, 跳过
n. 蹦跳, 跳跃
[近义词]：
v. jump, leap, bound, spring, move
n. jump, dance
[惯用语]：
hip hop 嘻哈文化
on the hop 到处奔忙；忙碌
hop off 起飞；离开
[例句]：
• The monkey is hopping on the trees.
这只猴子在树上跳着。
• Just then a little rabbit hops by.
这时候，一只小兔子跳了过去。
