And the scientists had good reason to be pessimistic: several years of animal cloning work had taught them that most cloned animals never even make it to birth, and the rare ones that do all too frequently have problems ranging from physical deformities t
And the scientists had good reason to be pessimistic: several years of animal cloning work had taught them that most cloned animals never even make it to birth, and the rare ones that do all too frequently have problems ranging from physical deformities t
科学家们如此悲观是有充分道理的：几年的动物克隆工作使他们明白，大多数克隆动物根本活不到出生的那一天，那些极少数能够顺利出生的动物往往有各种问题－－从身体畸形到危及生命的种种疾患。