What is necessary for a convection cell to be set up in a fluid?

What is life ? a: hell b: gods bible c: or depression

Healing after the death of a loved one is most difficult when: a) the bereaved is not allowed to mourn in the way he or she wishes b) the death is a long, protracted one c.) a period of grief has already elapsed d) no other mourners are present

How are 3-d printers useful in studying evolution? a. to color the fossils of organisms b. to create clones of extinct organisms c. to create replicas of fossils d. to prepare paper cutouts of organisms e. to study the composition of fossils