Spaceship 2060 continues its flight to the planets, this time to ______. Al Biruni  and his ______ were wondering all the flight about the nature of this _______. They have many questions on their minds: What does Mars look like? What does its surface look like? What do the ______ do? They were so excited to discover the _______ of gases surrounding the planet.

●      Mars is the 4th planet from the Earth.

●      It is more than 225 million kilometre from the Sun.

●      A day on Mars is 24.6 hours.

●      An evidence of a lake under its south polar ice cap was discovered in 2018.

●      Viking Landers was the first spacecraft to land on Mars in 1976.

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Question 2: ______________________________________________________________________

Question 3: ______________________________________________________________________

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Question 5: ______________________________________________________________________

The Egyptians were the first people to use a paste to clean their teeth around 5000 BC. But the first modern toothpaste was invented in 1824 by the dentist, Peabody. The first commercially produced toothpaste was sold in a jar in 1873.

Toothpastes mainly contain water, abrasives, including aluminum hydroxide, calcium hydrogen phosphates, calcium carbonate, silica, hydroxyapatite and fluoride.

(a)  sour and sharp to the taste
 (                    )

(b)  substances that react with acids to form salt  (                           )

(c)   orange, lemon, and grapefruit   (                        )

(d)  connected with buying and selling, and making a profit               (                       )

(e)   substances used for polishing or cleaning a hard surface.  (           )

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(b)  Using the simple past
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