1. If you purchase 200GE shares of $60 per share with margin. If initial margin requirement and maintenance margin ratio (Maintenance margin requirement) is 50% and 30% respectively. (1) When the stock price of GE falls to what level, you will receive the margin supplement notice? How much margin do you need to make up at this time? (2) If the stock price of GE becomes $80, ignoring the loan interest rate, and no dividend is paid during the period, what is your return on investment? (3) If you short sell 200 GE shares, how much guarantee do you have to pay Jin? It is assumed that the initial margin rate and guarantee maintenance rate remain unchanged. When the price of GE stock changes, you will receive a margin supplement notice? How much insurance do you need to pay at least at this time Certificate? (4) If GE shares become $45 per share, what is your return on investment through short selling