Related Clues:

• Sch. course concentration
• Fi lead
• Subj. of three of the six Nobel Prizes
• Poly-___ (college major)
• Noted twin
• Half a celebrated set
• Coll. major
• Our lang.
• A Siamese twin
• Grade sch. class
• See 35-Across
• ___-fi
• Biol., e.g.
• See 21-Across
• One of the Bunker twins