Little Tom _____finished his homework; otherwise, he wouldn’t be listening to music.[ ]

To my surprise, he was lost in thought then and not ____ of my presence at all.

1He kept his head _____ water when he began to learn swimming, but he raised his head now and then

下列各项中对“诚”的解释，正确的一项是（ ）①乃能衔哀致诚②诚知其如此③所谓天者诚难测④而神者诚难明矣

Mrs. White found her husband ___by letters and papers and___ very worried.