Penguins (a)   during the cold Antarctic winter. (sinh sản)

Birds usually (a)   with one partner during the breeding season. (giao phối)

The eggs will (a)   after about three weeks. (nở trứng)

The penguins (a)   together to stay warm. (tụ lại, quây quần)

A (a)   of ants built a large nest underground. (đàn, bầy)

The rainforest is a rich (a)   full of life. (hệ sinh thái)

There is a strong (a)   between plants and animals in nature. (sự liên kết)

A lion’s (a)   mainly consists of meat. (chế độ ăn)

Plants are (a)   because they make their own food. (sinh vật sản xuất)

Rabbits are (a)   that eat plants. (sinh vật tiêu thụ bậc 1)

Snakes are (a)   that eat small animals like frogs. (sinh vật tiêu thụ bậc 2)

Eagles are (a)   at the top of the food chain. (sinh vật tiêu thụ bậc 3)

The caterpillar eats the (a)   of plants. (lá)

Mammals are covered in (a)   to keep warm. (lông, tóc)

The frog’s tongue is (a)   to catch insects. (dính)

Water is the most common (a)   on Earth. (chất lỏng)

The Venus flytrap can (a)   insects inside its leaves. (bẫy)

The crab uses its claws to (a)   shells. (nghiền, ép)

The plant releases (a)   to digest its prey. (dịch, nước)

Sugar can easily (a)   in hot water. (hòa tan)

Humans (a)   food using enzymes in the stomach. (tiêu hóa)

The teacher showed (a)   of the human body. (sơ đồ, biểu đồ)

Scientists took (a)   of the new bird species. (ảnh chụp)

Scientists took (a)   of the new bird species. (ảnh chụp)

The class used a (a)   of the solar system. (mô hình 3D)

Students observed (a)   such as rocks and shells. (vật thật)

We watched (a)   about ocean life in class. (video)

Fish, birds, and mammals are all (a)   . (động vật có xương sống)

Dolphins must come to the surface to (a)   . (thở)

Polar bears have thick (a)   to keep them warm. (lông mượt)

Fish use (a)   to breathe underwater. (mang)

Humans and whales both use (a)   to breathe air. (phổi)

Reptiles are covered in (a)   for protection. (vảy)

Frogs can absorb water through their (a)   . (da)

The fish moves quickly using its (a)   . (vây)

The turtle hides inside its (a)   when frightened. (vỏ cứng)

Birds use their (a)   to fly and stay warm. (lông vũ)

A snake lays its (a)   in the sand. (trứng)

A (a)   of dolphins swam past the boat. (một đàn cá heo)

Whales eat tiny (a)   in the ocean. (sinh vật phù du)

A mule is a (a)   between a horse and a donkey. (con lai)

Dolphins use sound at different (a)   to communicate. (tần số)

Sound is measured in (a)   . (đơn vị đo tần số)

The ship used (a)   to detect submarines. (thiết bị định vị âm thanh dưới nước)

(a)   study life forms that live in the ocean. (nhà sinh vật biển)

The Pacific (a)   is the largest in the world. (đại dương)

The animals were rescued and moved to a wildlife (a)   . (khu bảo tồn)

Scientists used a (a)   to follow the whale’s movements. (thiết bị theo dõi)

Birds travel long distances during (a)   . (sự di cư)

Tigers are an endangered (a)   . (loài)

Researchers placed underwater (a)   to record whale sounds. (micro thu âm)