a我在开会。 I am holding a meeting.[translate] a这个对我来说很难 This is very difficult to me[translate] aIt'raining in our city and I'm writing to you It'raining在我们的城市和我书写 对您[translate] abeautifui woman kissing you 亲吻您的beautifui妇女[translate] ...
Systematic design of two-group refractive zoom lensesThe two-group zoom lens is the simplest arrangement which is capable of achieving a modest useful zoom range and adequate aberration correction for practical implementation. The first order layout of these systems is straight-forward and the real ...