Which of the following events occurred during the first trimester?
a. heart beat begins
b. lungs fully develop
c. bones become solid
d. fetus moves and kicks and swallows

Compare the depth of field when focusing with low power and high power. which power has the greater depth of field?

Ascientist is conducting an investigation that involves water, silver, carbon dioxide, and oxygen gas which group of statements best describes all of the materials he is using in the investigation?

Where are the strongest jet streams located?