阅读理解

The passage is mainly(主要地) about       

阅读理解
Jacks is the name of a game that is quite popular with children. To play jacks you will need a small rubber
ball and then small metal objects(物体) called jacks.
The rules for this game are not complicated(复杂). To begin, you put the ten jacks on the floor or ground
in front of you. Throw the ball up but not too high, pick up one jack, and then catch the ball. Keep the jack
in your hand and then go on picking up the other jacks one at a time. You lose your turn if you do not
catch the ball, you do not pick up a jack or you drop any jacks from your hand.
When you finish all ten jacks, you now try to do the same thing again but with two jacks at one time. This
is more difficult, of course. You lose your turn if you make any of the other three mistakes or if you do
not pick up exactly(准确地) two jacks each time!

A good title for this passage is       .

阅读理解
Can earthquakes(地震) be predicted(预测)? The answer may be “yes” because we have
helpers - animals.
......
Scientists(科学家们) want to know what warnings(预兆) the animals sense(感觉). They
know that animals sense more than(比……多) humans(人类)do. Many animals can see,
hear and smell things that people do not even notice(注意).Some can sense small changes
(变化) in air pressure(大气压) or gravity(重力).This sense helps animals predict quakes.
Scientists do an experiment(实验).They put some dogs in a room with earthquakes. (Small
quakes often come before or after a large one.) There is a low sound before each quake.
Each sound makes the dogs bark(大叫). A scientist looks at his machine(机器). It seems
(看上去) there is a loud noise, too. The scientist finds that the dogs can sense quakes, but
humans feel and hear nothing.
......

The scientists do an experiment with a group of dogs to       .