I am so disappointed about myself!

Today!I was totally defeated!
I am frustrated!I am discouraged!
It is not the problem about whether i have studied hard or not..
I have done my very best to strike for the goal`
but i am just very confused`
why my result was not that good?!
may i say...not that good to be compared wf my classmates`
Take today's Biology quiz as an example`
i have tried hard`i have studied`i totally followed what ms liu taught in class`
but i felt lost when i was doing the quiz`
i could't even realize that the unicellular algal cells were plant cells!!!!
what's going on!!!!!!
have you used your brain at all peony?!
i will fail this quiz i guarantee!
Is that what i am going to face in my HKCEE?!
Is that the same case for me?!
Lost...afraid...puzzled...
How can i make a stand for myself in 4D?!
Oh`this sentence spoiled out again...same case when i was in 2D`
I feel like a loser`not an expert in either subject!
I am only a student wf an average performance in Science class`
is that what i want?
I am afraid...what can i do?!
Anybody help me?!