I know the basics about the difference in the usage between は and が.
Nevertheless, when it comes to more complex sentences, I encounter
difficulties that I want to explain on base of some examples. Maybe, somebody
can briefly confirm whether my understanding is correct.

  1. > _Looking at the X-ray image, it is apparent that the package of the component described above cracked._
>
> X線写真によると、前述の部品 **は** 、パッケージが亀裂が生じた **ことが** 明らかです。

I think it is clear that "前述の部品" is the topic and can or should be marked with
"は".

  2. > _It is no doubt that the package of the component described above cracked._
>
> 前述の部品 **の** パッケージが亀裂が生じた **ことは** 疑いようがありません。

Although the constructions of both sentences are very similar, "疑いようがありません"
must be preceded by "ことは" and "前述の部品" cannot be the topic and hence becomes a
genitive.

  3. > _Assuming that the temperature of the device described above excessively increased, the failure picture can be explained._
>
> 前述の部品 **が** 過度な温度上昇となっていった **という仮定のもとで** 、不具合品の写真は、真実味が出てきます。

I am sure that "前述の部品" cannot be marked with "は" but can anybody explain me
why? Can the part of the sentence preceding "仮定" be regarded as relative
clause where "は" is not permitted at all?

Is this sentence correct?

> 前述の部品 **は** 過度な温度上昇となっていった **と仮定すると** 、不具合品の写真は、真実味が出てきます。

  4. > _It is reasonable to think that the improvement measure described above guarantees protection for the components._
>
> 前述の改選策 **が** 本部品用保護を保証している **と考えることは** 、妥当なように思われます。

"前述の改選策" cannot be marked with "は" because this could run counter to the
"と考えることは".

I highly appreciate your collaboration. This "は" versus "が" topic is my main
concern.
CC BY-SA 3.0
2017-03-18T14:54:58.890
44576
2017-03-20T05:56:36.883
2017-03-20T02:33:52.993
20328
20328
question
grammar particle-は particle-が は-and-が topic
More complex sentences - When to use は? When to use が?
1. Yes, your understanding is correct.

  2. First, I want to correct the Japanese sentence.

> 前述の部品のパッケージ **に** 亀裂が生じたことは疑いようがありません。

"疑いようがありません" doesn't have to be preceded by "ことは". Appending "こと" in the end
of a Japanese sentence is roughly equivalent to putting words "The thing that"
or "The fact that" in the beginning of English sentence. It make a sentence a
noun.

> 亀裂が生じた(a crack appeared.) [sentence]  
>  亀裂が生じたこと(a fact of a crack appeared.) [noun]  
>  亀裂が生じたことは間違いありません。(There is no doubt about the fact of a crack appeared.)
> [sentence]  
>

After my correction, "亀裂" is a topic in the sentence.

  3. Yes, "前述の部品" can be marked with "は". The following sentences are both correct, but a little difference on nuance.

> 前述の部品 **が** 過度な温度上昇となっていったという仮定のもとで、不具合品の写真は、真実味が出てきます。  
>  You only think of "前述の部品" and make assumption.  
>
>
> 前述の部品 **は** 過度な温度上昇となっていったという仮定のもとで、不具合品の写真は、真実味が出てきます。  
>  You want to make assumption on the "前述の部品", but other "部品".

To compare with the 2nd sentence of the above, I'd like to add this sentence.

> 前述の部品 **も** 過度な温度上昇となっていったという仮定のもとで、不具合品の写真は、真実味が出てきます。 You want to make
> assumption on the "前述の部品", but also other "部品".

Yes, the following sentence is correct.

> 前述の部品 **は** 過度な温度上昇となっていったと仮定すると、不具合品の写真は、真実味が出てきます。

Note that you can change bold **は** above to **が**. The difference is the same
as what I describe above.

  4. First off, I think "改選策" is probably typo for "改善策". "改選" means "re-election", and "改善" means "to improve".

And it is more natural to write "本部品の保護" rather than "本部品用保護".

"前述の改選策" could be marked with "は", but it make the sentence bad as the
sentence contains 2 noun marked with "は". (But you still can't say the
sentence is incorrect.)

> 前述の改善策 **は** 本部品の保護を保証していると考えること **は** 、妥当なように思われます。

The setence above is somewhat confusing sentence. It is recommended to avoid 2
noun marked with "は", you should changed one of "は" to "が". The following
sentences are both correct, but nuance is a little different.

> 前述の改善策 **は** 本部品の保護を保証していると考えること **が** 、妥当なように思われます。

You are not sure with the other "改善策" contribute, but at least it is the
reasonable idea(考えること) that "前述の改善策" contributes.

> 前述の改善策 **が** 本部品の保護を保証していると考えること **は** 、妥当なように思われます。

You are not sure with the other reasonable idea(考えること) exists, but at least
you are sure that "前述の改善策" contributes.
CC BY-SA 3.0
2017-03-19T05:19:52.900
44597
2017-03-19T05:19:52.900
9608
44576
answer