Which contraction correctly completes the sentence? some competitors able to finish the race. a. wasn't b. weren't

What is the best revision of this statement from the body of a cover letter?

Biologists recognize five levels of cell organization. the lowest and simplest is the cellular level. organisms here are either unicellular organisms, like protozoa, or colonial organisms. colonial organisms are composed of single-celled individuals that stay together to sustain the life of the whole colony. next on the scale of complexity is the level occupied by tissue. a tissue is a group of similar cells which perform a similar activity. tissues that are organized around a common function together make up an organ, the third level of complexity. the fourth level of organization is the system, formed by a group of organs which together perform a specific bodily process. the fifth and highest level is the organism level, in which body systems work together in a structure capable of independent life. main idea:

Look at this photograph of a klondike gold rush camp. what would you find challenging about being in this type of environment? check all that apply. the extreme cold the steep climbs over the mountain the thick covering of snow the cramped living conditions the harsh winds