1, 15-year-old Xiao Chen went to a bar with friends and took some drugs under the demonstration of friends. Since then, Xiao Chen has often smoked. After a period of time, Xiao Chen's thinking was slow, his logic was confused, his memory declined, and sometimes he giggled, and his academic performance dropped sharply. According to the description, the drug Xiao Chen took was probably marijuana.

2. There is a saying called "drug addiction for one day, drug addiction for ten years, drug addiction for life", which is used to illustrate drug addiction (c).

3. "Bad family environment has a great influence on teenagers' drug abuse. Among drug addicts, many families have many problems. " This sentence is more in line with the environmental factors caused by drug abuse (the influence of family environment).

In a village, every family has drug addicts. This reflects the environmental factors of drug abuse (the influence of community environment in C).

When investigating many drug addicts, we found that the first reason for drug abuse is. (d) Blind curiosity, pursuit of pleasure and excitement.