`4)`

`=>` About 2000 gallons of blood are pumped through our bodies

`5)`

`=>` 17 muscles are used to smile and 43 are used to frown

`6)`

`=>` About 32 million bacteria are estimated live on one square inch(2,5 cm²) of our skin 

`7)`

`=>` Emotional tears are produced

Cấu trúc câu bị động

Hiện tại đơn

S + am/is/are + P2 + by O

Hiện tại tiếp diễn

S + am/is/are + being + P2 + by O

Hiện tại hoàn thành

S + have/has + been + P2 + by O

Quá khứ đơn

S + was/were + P2 + by O

Quá khứ tiếp diễn

S + was/were + being + P2 + by O

Quá khứ hoàn thành

S + had + been + P2 + by O

Tương lai đơn

S + will + be + P2 + by O

Câu bị động `-` Thì HTĐ : S + be + V3 / PII ( by O )

`4`.About 2000 gallons of blood are pumped through our bodies by a heart everyday

`5`.17 muscles are used to smile and 43 to frown

`6`.About 32 million bacteria are estimated live on one square inch ( $2.5cm^{2}$ ) of our skin by scientists

`7`.Emotional tears are produced by humans only

`\text{@ TheFox}`