例句與造句

1. Beals studied at Yale University earning a B . A . in 1960, an M . A . in 1962, and a Ph . D . in 1964 under Felix Browder with thesis " Non-Local Boundary Value Problems for Elliptic Partial Differential Operators ".
2. It's difficult to find elliptic partial differential operators in a sentence. 用elliptic partial differential operators造句挺難的