eeth.Р67. How may cause reasoning go?РCause reasoning may go _____________ or from effect to cause.Р68. Are causes classified as necessary, sufficient, or contributory?Р___________.Р69. What does a sufficient cause mean?РA sufficient cause is one which can produce an effect unaided, though there may be ________. Р70. What is it usually necessary to do in establishing or refuting a causal relation?РIn establishing or refuting a causal relation it is usually necessary _______by which the alleged cause produces the effect.РIV. Writing (30 points)РDirections: For this part you are allowed 30 minutes to write A Letter of Gratitude in English about 100 words expressing your thanks for your friend’s kindness. You should write based on the outline (in Chinese)given below.Р1.简单表示事因;Р2.表示感谢并希望有回报机会。