1，2B 3D 4C 5D 6A 7B 8B 9C 10D

Second, fill in the blanks

1 1, 3.24× 106 12, 10 13, 2: 3 14, 15, 3/5.

16、24

Third, answer questions.

17,218,1219, (omitted) 20,2 √ 7+5+√ 3.

2 1, the original formula = x-2 =-322, (1)y=x+2 y= 8/x (2) 1.

23 (1) * * 3 ÷ 25% = 36 (bar), with an average of 36÷(2+2+3+4+ 1)=3 (bar). There are four people in the supplementary picture.

(2)7/ 12

24. If it is known that (1) connected DM has △MAD all equal to △MFC, then ∠CME=∠DME, ∠ADM=∠DMC, ∠AMD=∠CME, then ∠AMD =∞.

(2) We can get1/2 ∠ FCM =1/2 ∠ ADM = ∠ CME and ∠ MPB = 90-∠ CME = 90- 1/2.

25.( 1) April y1= (1/5) x+1.8 May y2=? (- 1/20)x2—( 1/4)x+3. 1

(2) April 1 kg profit w 1 = (-1/20) x+0.6May1kg profit w2 = (-1/20) x2-(1/)

April and May are the first week with the biggest profits, which are 0.55 and 1 respectively.

(3)a=8

26.( 1) When 0 < t < 2/3, y = (-3 √ 3/4) t2+(√ 3/2) tWhen 2/3 < t < 2 √ 3/3, y = (3/2) t2-t.

(2)D 1 (2√3/3，0) D2 (2/3，0) D3(√3/3， 1)

(3) Take a point H on the extension line of BO to make OH=NA, connect CH, make △ANC all equal to △OHC, △MNC all equal to △MHC, and MN=MH, so that the circumference of △BMN remains unchanged, and the circumference is 4.