Long-term use of can lead to permanent hearing loss, limb spasms, nervous system and brain damage, bone marrow damage, and death.
a. heroin
b. dextromethorphan
c. inhalants
d. cocaine

Answer(a) one needs to learn from experts and be determined to be the best in the field;

Answer(1) year suspended

Dhope it

After spending all that time on the research then by all means modify the hypothesis or aim by reporting such. for example the findings did not bring forth what was expected but brought about different yet interesting findings worth exploring so the hypothesis is changed to reflect this new findings.

i may be way off but.