Question

1. handle chemicals carefully. 4. no ________ in the lab! all directions.

Explanation:

To solve this fill - in - the - blank for a lab - related sentence "No ______ in the lab!", we can consider common lab rules.

Step 1: Analyze common lab prohibitions

In a laboratory, common prohibitions include actions like "eating", "drinking", "running", "horseplay" etc. A very common and standard phrase for lab safety is "No eating or drinking in the lab!" or just "No eating" / "No drinking" / "No horseplay" etc. If we consider the most general and common one, "eating" or "drinking" or "horseplay" can be used. But a very typical answer for this kind of lab safety sentence is "eating" (or "drinking", "horseplay" etc. But "eating" is a very common one).

Step 2: Fill in the blank

Based on the common lab safety rules, we can fill in the blank with "eating" (or other appropriate actions like "drinking", "running", "horseplay" etc. But "eating" is a very standard answer for this structure).

Answer:

eating (or drinking, horseplay, running etc. ; "eating" is a common standard answer)