1. Being sick, he didn't go to school.

2. Because he was sick, he didn't go to school.
(Can we use both expressions? Are they the same?)

3. Being sick, he went out to play soccer.
4. Though he was sick, he went out to play soccer.
(What about these two sentences? Can we use both sentences? Are they grammatical and have the same meaning?)

2 and 4 are correct, 1 and 3 are incorrect.

Actually, #1 is acceptable. #3 doesn't really make sense, so I find it unacceptable. "Being sick" and "Because he was sick" do mean the same thing. To rephrase #3, you might write, "Despite being sick..." or "Although he was sick..." In #4,"Although" is better than "Though".

1. Being sick, he didn't go to school.

2. Because he was sick, he didn't go to school.

Both of these expressions convey the same meaning, but they have different structures. Let's break them down:

1. "Being sick" is a present participle phrase that functions as an introductory phrase. It describes the subject of the sentence ("he") and provides the reason why he didn't go to school. This expression is grammatically correct.

2. "Because he was sick" is a subordinate clause that begins with the conjunction "because." It also explains the reason for his absence from school. This expression is also grammatically correct.

In terms of usage, both expressions are acceptable and commonly used. However, the first expression (Being sick, he didn't go to school) might sound slightly more formal or literary, while the second expression (Because he was sick, he didn't go to school) is more commonly used in everyday language.

3. Being sick, he went out to play soccer.
4. Though he was sick, he went out to play soccer.

In these two sentences, both convey the same meaning as well. Let's analyze them:

3. "Being sick" is a present participle phrase that functions as an introductory phrase. It describes the subject of the sentence ("he") and provides a background circumstance for the main action, which is going out to play soccer. This expression is grammatically correct.

4. "Though he was sick" is a subordinate clause that begins with the conjunction "though." It acts as a concessive clause, meaning it presents a contrast with the main action. This expression is also grammatically correct.

Similar to the previous expressions, both sentences are acceptable, but their usage might vary. The third expression (Being sick, he went out to play soccer) may be seen as more formal or literary, while the fourth expression (Though he was sick, he went out to play soccer) is commonly used in everyday language.