Answer:
He can cry.
Step-by-step explanation:
What the speaker in Sonnet 30 by William Shakespeare mean when he says that he can "drown an eye" is that he can cry. In Sonnet 30 the speaker is looking back on his younger days. He regrets he could not achieve what he wanted and all the wasted time of his youth and that can make him cry, although he is not used to crying. He also regrets the loss of friends that are now dead. But when he thinks of his dear friend he rejoices and his losses are compensated.