すら / ですら

すら means "even": it picks out an extreme case, and the reader concludes that everything less extreme follows. It goes straight after a noun, taking the place of が or を, and belongs to writing and formal speech.

Most sentences with すら are negative or critical: even the most basic thing did not happen. A positive sentence is possible when the point is how easy or widespread something is.

すら or ですら

ですら is the form for a person who does or knows something, the subject of the sentence: "even experts", "even a child". すら alone goes on things and actions.

Other particles stay in place and すら follows them.

• × 友達すら本当のことを言えなかった → 友達にすら本当のことを言えなかった

すら or さえ

さえ means the same and is the word for conversation. すら sounds written. さえ also has a conditional use, さえから～ば, "as long as", which すら does not.

• × 時間すらあれば → 時間さえあれば