一手

The reason why I am here is that I wish to lend a hand.

He prides himself on his cooking skill.

He is quite adept at taking photos. / He is quite a dab at photography.

be proficient in one's trade; know one's stuff

write a fair hand

show off one's skill

be very skilful

What a vicious trick he played!

I can't help you. You brought this on yourself.

bring a child up all on one's own

start/provoke a dispute all by oneself

foster single-handedly

plot single-handedly

We must always work for material progress and at the same time for cultural and ethical progress; we should develop the economy and at the same time strengthen democracy and the legal system; we should promote reform and opening to the outside world and at the same time fight crime and punish corruption.

One round lot is 100 shares of stock.