Before conducting an experiment, the scientists needs to review what ?

The scientist needs to review his notes or make  hypothesis of somehing or someone

results of other experiments related to the subject

Explanation:

it means

miss jennifer is buying pencils in packs of 12, notebooks in packs of 16, and red pens in boxes of 20. she needs to have the same number of pencils, notebooks, and red pens. how many packs of each type should she buy?

answer mine : )

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.