If the time is the past, the action of condition clause has been done and
the main action happened unexpectedly. For example, "When i went to
the deartmentstore, it happened to be not open."
きのう デパートに 行ったら、 やすみでした。
Besides if the time is future, たら expresses supposition. So you say "If
it is sunny tomorrow, let's play tennis."
あした はれたら テニスを しましょう。
If the stuation is expected to actually happen, nothing hinders you ftom
arriving at the station, You say "I'll call you when I arrive at the
station."
駅に ついたら でんわを します。
You can use "nara" when you know the condition is determined,. Under the determined condition,
you say about your action or thought. For example, you know that your friend
difinitely decided to buy a TV set. and you can advice him .
テレビを 買うなら あきはばらが やすいですよ。
"ba" is used when there are two condition. But you can not decid to choose
one this moment. So you use "ba” ば like following. I don't know if
Michiko go to the party or not. "I will go if Michiko comes."connotate
that I will not go to the party if Michiko doesn't go ,
みちこさんが パーティーに 行けば わたしも 行きます。
"to" marks a condition that brings about an noncontrallable events and state
like natural phenomena. Under a condition, the phenominon always happens.
For example, we never contrall when cherry blossoms bloom and how to buy
a ticket.
春になると さくらが さきます。
この ボタンを おすと きっぷが 出ます。
Let's Practice !
Exercise
1、ばba: there are two condition this moment.
Example おとこの こが (うまれる) マイク、 おんなの こが(うまれる) ヘレンと なまえを つけよう。
おとこの こが (うまれれば) マイク、おんなの こが (うまれれば) ヘレンと なまえを つけよう。