A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

leave someone with something • leave something
with someone
leave someone with something —leave a person in possession
of smth. that may be a burden or responsibility: He asked me
to hold this parcel for him a moment, then he went off and
left me with it.
leave something with someone —leave smth. in a person’s care:
You won’t actually get to speak to the minister but you can
leave a message with his secretary.
lecture at someone • lecture to someone
lecture at someone —talk to a person in a sententious,
pompous manner: He doesn’t talk to you if you approach him,
he lectures at you pedantically.
lecture to someone —give a formal talk (to a group of stu-
dents, etc.): He still finds the time to make frequent visits to
Rio Grande University where he lectures to students in the
School of Business.
Note: 
The expression does not fully correlate in meaning with
the phrase lecture someone—
1
. reproach or scold a person: He
left the room, coming back only minutes later to lecture me
for not cleaning off the counter after doing the dishes. 2. =
lecture to someone: When Krastins lectures his students on
Greco-Roman palaces or baroque churches, he turns to pho-
tographs.
lecture in something • lecture on something
lecture in something —give lectures in a subject to a group
of students: Dr. Watson lectures in English literature.
lecture on something —
1
. lecture to students on a specific
topic: This term he is lecturing on the nineteenth-century
novelists. 2. give a long talk on a topic to a group of people:
He goes round the country lecturing on the evils of drink.
left at the mercy of someone • left to the tender
mercies of someone
left at the mercy of someone —left in smb.’s absolute power:
Once the Roman army withdrew, England was left at the
mercy of various marauding tribes.
left to the tender mercies of someone —(ironic) left to be dealt
with by smb. who is not likely to show any kindness or sym-
pathy: I found her father left to the tender mercies of the sav-
ages, deserted by you in the bush.