Never exert when inserting glass tubing into a rubber stopper, always lubricate the glass with glycerin first.

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.

Answerrestate the main idea,essay or thesis, summarize the three subpoints of your essay, leave the reader with an interesting final impression;