Answer:
1- It's often impossible to repeat trials on the same subjects. 2-Subjects may report an inaccurate medical history. 3-It can be difficult to control all possible variables. 4-It's impossible to come up with testable scientific questions for human subjects.
Explanation:
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The correct answer is the air chambers in the bird skeletons. First of all, both reptiles and birds have amniotic fluids; and this cannot be documented by fossil studies. While it is true that birds do not have reptilian scales, this cannot be documented by fossil studies too. Warm bloodedness of birds and cold bloodedness of reptiles cannot also be documented by fossil studies. Air chambers in the bird skeleton, on the other hand, can be seen as fossil evidence and differentiated with reptilian skeletons with no air chambers.
Answer: If people say humans evovled from monkeys..why are monkeys still HERE?????????????????????????????????????????
Answer:
Yes it has actually because with more humans being born everyday there is not enough space for everyone that is planning on coming out.
Photosynthesis is the answer.. I hope this helps... could you mark brainliest?