The word or phrase that serves as a context clue for the word "contaminate" is "keeping his laboratory clean."
In this context, the phrase "keeping his laboratory clean" can be considered a context clue for the word "contaminate" and helps us understand its meaning. The contrast of keeping the laboratory clean and the mention of procedures suggests that "contaminate" involves something that would disrupt or spoil the cleanliness or purity of the laboratory. To confirm this, we can consult a dictionary.
The word or phrase that serves as a context clue for the word "contaminate" is "keeping his laboratory clean." This phrase implies that the word "contaminate" refers to something that would go against the goal of maintaining a clean laboratory. In other words, "contaminate" means to introduce impurities or harmful substances into an environment that should be free of them.
