Science

A force is a push or a pull on an object.√

A force changes the motion of a moving object.√

A force can be strong or weak, and it always has a direction.√

The Earth is a planet that goes around the sun in a circular orbit.√

The speed of its motion doesn't change, but the direction of its motion does.

The Earth has a layer of gas above its surface, which helps to support life.

Atoms are the building blocks of matter.√

At the center of an atom is its nucleus, which has a positive(正极) electric charge.

Outside the nucleus are electrons, which have a negative(负极) charge.

Asteroids and comets are objects that orbit our sun but are smaller than planets.

Asteroids that pass close to the Earth are called near-earth objects.

The layer of gases just above Earth's surface is our atmosphere.√

The atmosphere is made up of gases, such as oxygen(氧气) and nitrogen(氮气).√

Without an atmosphere, there would be no life on Earth.√听选What changes the motion of a moving object? - A force changes the motion of a moving object.听选what is made up of gases, such as oxygen and nitrogen? -The atmosphere is made up of gases, such as oxygen and nitrogen.听选What has a nucleus and an electrons? -Atom has a positive charge nucleus and a negative charge electrons.听选What objects orbit our sun but are smaller than planets? -Asteroids and comets are objects that orbit our sun but are smaller than planets.听选what planet orbit of the sun? -the earth填空A force changes the motion of a moving object.填空At the center of an atom is its nucleus, which has a positive electric charge.填空Without an atmosphere, there would be no life on Earth.听说A force changes the motion of a moving object.(86)听说Without an atmosphere, there would be no life on Earth.(80)看说The Earth has a layer of gas above its surface, which helps to support life.(78)看说If they collide with Earth they could cause an extinction event. (75)

听说：what can be strong or weak, but we always have a direction? -A force can be strong or weak, and it always has a direction.

听说：what is help together by electric force? -

听说：what would

A force can increase or decrease the speed of an object, and it can change the direction of motion.

The electric force between the nucleus and the electrons holds the atom together.

听说Without an atmosphere, there would be no life on Earth.(84)

A force is a push or a pull on an object.

Atoms are the building blocks of matter.

The Earth has a layer of gas above its surface, which helps to support life.

What is the layer of gases just above Earth's surface? -The layer of gases just above Earth's surface is our atmosphere.

What keeps the Earth in an orbit around the sun? -It moves in an orbit around the sun because of the gravitational force between them.

填空A force can increase or decrease the speed of an object, and it can change the direction of motion.

填空The electric force between the nucleus and electrons holds the atom together.

Asteroids that pass close to the Earth are called near-earth objects.

听说A force is a push or a pull on an object.(77)

填空Without an atmosphere, there would be no life on Earth.

At the center of an atom is its nucleus, which has a positive electric charge.