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

Note: 
The expression does not correlate in meaning with the
phrase live line—(also: live wire) a cable or wire carrying electric
current: Safe work procedures require the use of rubber gloves
and other live line tools.
line of life —
1
. = lifeline 3: Had I been a gypsy palmist I
might have paid more attention to the old grouch’s lines of
life and fate. 2. occupation; line of business: His father being
a physician, he also decided to follow in his footsteps and so
began the preparation for this line of life. 3. (dated) one’s rank
or station in life: She had received a more liberal education
than is usually bestowed upon English women in the middle
line of life.
lifetime • time of life
lifetime —
1
. the period during which a person, plant, or ani-
mal is alive: Bigamy —marriage with a second wife or husband
during the lifetime of the first. 2. the duration of a thing or a
thing’s usefulness: The Viking spacecraft will consist of an
orbiter and a lander, each with a lifetime of many months. 3.
is used to hyperbolically designate an exceedingly long time:
I got complications, had ups and downs. I was a lifetime in
that ward.
time of life —a particular period in a person’s life: He handles
it with the delight that a new mental toy inspires in most men
at a certain time of life.
See also: one’s time of life / time of one’s life.
lift the lid off something • put the tin lid on
 something
lift the lid off something —(also: take the lid off something)
expose or reveal smth. scandalous, shocking, etc. that has been
hidden: They are all set to release their explosive video which
will lift the lid off their work as undercover agents.
put the tin lid on something —(also: put the lid on something)
cause a plan, an activity, etc. to end: It’s got to be said that
our last two results could well put the tin lid on our hopes.