Yes, the Saale is navigable for a portion of its length. It is used for recreational boating and tourism in some sections, but it is not a major waterway for commercial shipping. **

The Main river is navigable for approximately 386 kilometers (240 miles) from its confluence with the Rhine river near Mainz to its source in the Franconian Alps. This stretch of the river is important for commercial shipping, with several major cities such as Frankfurt and Würzburg located along its banks. The Main river is a key transportation route for goods and passengers in the region, and its navigability plays a crucial role in the economy of the area. **

The Congo River is not navigable throughout due to a number of natural obstacles such as rapids, waterfalls, and cataracts. These obstacles make it difficult for boats and ships to navigate the river safely and efficiently. Additionally, the river passes through dense rainforests and swamps, further complicating navigation. The presence of these natural barriers makes it challenging to develop a continuous and reliable transportation route along the entire length of the Congo River. **

Possible symptoms of a brain tumor can include headaches that are more severe or frequent than usual, seizures, changes in vision or hearing, difficulty with balance or coordination, changes in personality or behavior, and weakness or numbness in the arms or legs. It's important to note that these symptoms can also be caused by other conditions, so it's important to see a doctor for a proper diagnosis. **

The symptoms of a brain tumor can vary depending on the location, size, and type of tumor. Some common symptoms may include headaches, seizures, changes in vision or hearing, difficulty with balance or coordination, and cognitive changes. The severity of these symptoms can vary, with some individuals experiencing more noticeable and severe symptoms while others may have more subtle or gradual changes. It is important to consult a healthcare provider if you are experiencing persistent or concerning symptoms that could be related to a brain tumor. **

No, the symptoms of a brain tumor are not always present. In some cases, a brain tumor may not cause any noticeable symptoms until it grows large enough to exert pressure on surrounding tissues or structures. Additionally, the symptoms of a brain tumor can vary depending on the location and size of the tumor. It is important to be aware of potential symptoms such as headaches, seizures, changes in vision, and cognitive changes, and seek medical attention if any concerning symptoms arise. **

No, dogs do not always have symptoms with a malignant tumor. In fact, many malignant tumors in dogs can go unnoticed for a long time because they may not cause any obvious symptoms in the early stages. Some dogs may only show symptoms once the tumor has grown large enough to cause discomfort or interfere with normal bodily functions. It's important for dog owners to regularly monitor their pets for any changes in behavior, appetite, or physical appearance, and to seek veterinary care if they have any concerns about their dog's health. **

The symptoms of a brain tumor can vary depending on the size, location, and rate of growth of the tumor. Some symptoms may come and go, while others may be more persistent. In some cases, symptoms may worsen over time as the tumor grows. It is important to consult with a healthcare provider for an accurate diagnosis and appropriate treatment plan. **