20．D——青夏教育精英家教网——

20．D

19．C　均为纯合体，即AABB、Aabb、aaBB、aabb自交。　

18．B

17．B

16．B

15．C

14．B

13．B

12．A　

11．C

0 186412 186420 186426 186430 186436 186438 186442 186448 186450 186456 186462 186466 186468 186472 186478 186480 186486 186490 186492 186496 186498 186502 186504 186506 186507 186508 186510 186511 186512 186514 186516 186520 186522 186526 186528 186532 186538 186540 186546 186550 186552 186556 186562 186568 186570 186576 186580 186582 186588 186592 186598 186606 447348