can someone proofread this?

~ This is the most common of models used by secondary school "students" in Hong Kong.

~ "I" had to give it to school and ask "to put on a label" printed with “H.K.E.A.A. APPROVED” before "I could use it in the examations".

~ The "dual" power system "generates the power with the" solar cell when the light is sufficient, "but" when the light is insufficient, the battery "automatically takes over the power functions".

~ The battery life was approximated "to" 3 years but I have been using it for 9 years, "since" 2006. It "is still working" well.

~ It "has" 2-line display,

(Note: beware of common splice and avoid run-on sentence)

~ Especially, by adding some of useful program commands, we can save "a lot of" time "on" "those" easy but repetitive calculations.
(save sb/sth from doing xx = 救 xx 免於 xx.)

~ We can "quickly and easily" recall the "previous" (or "last") executed formulas for editing. (previously executed formulas = all formulas executed before)

~ And of course, if you "need to remember" some data, constants or values, this function will help you a lot.

~ It is available values and programs memory, what is more, it can memorize my friends and my student life memories. (something is wrong but I don't know what you intend to mean..)

~ This calculator is "like" my comrade "to me" as it has been (X) with me "since" a long time "ago" (or, "for a long time") and helped me (to X - optional) overcome a lot of difficult challenges.

~ You know, examination is like a battlefield. I've survived and I wish it (my calculator) will too. I cannot do many things ("leave home") without it.

2015-05-12 01:48:35 補充：
(Note: beware of comma splice and avoid run-on sentence)

I am going to introduce Casio fx3650p which is a programmable scientific calculator manufactured by Japanese company, Casio computer co. ltd., and made in China.
This model is approved by the Hong Kong Examinations and Assessment Authority and can be used in the Hong Kong Diploma of Secondary Education Examination which is a university entrance examination of Hong Kong. This is the most common of models used by secondary school in Hong Kong. I bought it while I was in the first year of my secondary school. We had to give it to school and ask for the pad-printed with the “H.K.E.A.A. APPROVED” after bought it.
This calculator is powered by a solar cell and a single button battery. The two-way power system; with either solar power when light is sufficient, or battery powered when light is insufficient. The battery's life was approximated about 3 years but I have been using it for 9 years, from 2006 till now. As It still works well as the day I first bought it. I hope it will be working fine during my university's period because it has a lot of useful functions.
It is using 2-line display, we can view the expression and its result at the same time. This calculator is available in 6 modes and it can hold up to 4 calculation programs, we can input and store our own program in memory. Especially by adding some of useful program commands, we can save much more time from doing easy but repetitive calculations.
Also every time we perform a calculation, the replay function automatically stores the calculation formula and its result in replay memory. We can quick and easy recall of previously executed formulas for editing. We can input values directly into seven variables, A through D, M, X and Y. Independent memory is convenient for calculating. And of course, if you got some data, constants or any values to remember these functions will help you a lot. Its available values and programs' memory, what is more, it can memorize my friends and my student life memories.

V e r y G o o d ! !