Tế bào thường đứng sát nhau tạo thành lớp, đáy tựa trên màng đáy là một trong những đặc

answer: 21

step-by-step explanation:

divide 630 by 30. 30 goes into 630 21 times

glacial erosion, the picking up and movement of earth beneath a glacier, is also referred to as plucking. erosion and transportation of individual pieces of bedrock, especially large "joint block occur as a result of this glacial erosion. plucking is type of erosion in which rocks become frozen into the bottom and sides of the glacier.as the glacier moves downhill it 'plucks' the rocks frozen into the glacier from the ground.