Answer: The virus weakens as time passes.
Explanation: The virus will weaken continuously during transmission, and will reduce its toxicity after several generations of transmission, without causing much harm to the human body.
A chromosome contains one long DNA strand.
B.
Answer:
silicon dioxide Si02 and diamond
Explanation:
because it's commonly found in nature
Answer:
http://mairscience.weebly.com/uploads/5/7/8/8/57880837/8th_grade_key_2015_sol_released_test.pdf
Explanation: